$79+ Cheap flights from Ontario (ONT) to Chicago (CHI)
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 9/21. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Sep 2 — Sep 91
Round-trip
1 adult, Economy
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Find cheap flights from Ontario to Chicago with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.3. Compare prices and book
Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheapflights Tip: The best prices from Ontario to Chicago are usually found in January or September, booked 85 days in advance, depart on a Wednesday or Saturday and return on a Wednesday
Cheap flight deals from Ontario to Chicago
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Best
Last-minute
One-way
Cheapest flights from Ontario to ChicagoExplore the most affordable flight options available from Ontario to Chicago. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 3, 2026.
Explore the most affordable flight options available from Ontario to Chicago. Find the lowest fares from popular airlines and budget airlines, with prices last updated on August 3, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/187:56 pm
ONT
- ORD
1 stop15h 40m
Frontier
Mon 8/317:05 am
ORD
- ONT
2 stops18h 45m
Frontier
Deal found 7/28![Frontier logo]()
$276
This Trip.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/218:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Mon 8/249:26 pm
MDW
- ONT
1 stop13h 10m
Frontier
Deal found 7/30![Frontier logo]()
$277
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/146:15 am
ONT
- ORD
1 stop16h 08m
Frontier
Wed 9/166:30 am
ORD
- ONT
2 stops12h 29m
Frontier
Deal found 7/29![Frontier logo]()
$277
This Frontier deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/248:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/309:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/28![Frontier logo]()
$278
This United Airlines deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/257:00 am
ONT
- ORD
Nonstop4h 10m
United Airlines
Tue 9/18:06 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 7/28![United Airlines logo]()
$278
This Frontier deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/238:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Mon 8/319:26 pm
MDW
- ONT
1 stop13h 10m
Frontier
Deal found 7/29![Frontier logo]()
$279
This Frontier deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/238:17 am
ONT
- ORD
1 stop9h 58m
Frontier
Sat 8/298:45 am
ORD
- ONT
1 stop12h 16m
Frontier
Deal found 7/29![Frontier logo]()
$279
This Frontier deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/288:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/309:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/31![Frontier logo]()
$280
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/511:19 am
ONT
- RFD
1 stop6h 43m
Multiple Airlines
Sun 11/81:08 pm
RFD
- ONT
2 stops36h 47m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$280
This Frontier deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/118:24 pm
ONT
- ORD
1 stop7h 14m
Frontier
Sun 9/138:55 pm
ORD
- ONT
1 stop12h 09m
Frontier
Deal found 7/31![Frontier logo]()
$280
This Frontier deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/218:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/239:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/31![Frontier logo]()
$281
This Frontier deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/239:33 am
ONT
- ORD
1 stop13h 16m
Frontier
Fri 8/282:41 pm
ORD
- ONT
1 stop11h 09m
Frontier
Deal found 8/2![Frontier logo]()
$281
Best flights from Ontario to ChicagoDiscover carefully curated flight deals from Ontario to Chicago that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 3, 2026.
Discover carefully curated flight deals from Ontario to Chicago that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 3, 2026.
This Delta deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/612:00 pm
ONT
- MDW
1 stop8h 36m
Delta
Tue 9/151:00 pm
MDW
- ONT
2 stops12h 47m
Delta
Deal found 8/2![Delta logo]()
$279
This United Airlines deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/145:00 am
ONT
- ORD
1 stop6h 14m
United Airlines
Mon 11/164:15 pm
ORD
- ONT
Nonstop4h 32m
United Airlines
Deal found 8/1![United Airlines logo]()
$279
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/511:19 am
ONT
- RFD
1 stop6h 43m
Multiple Airlines
Sun 11/81:08 pm
RFD
- ONT
2 stops36h 47m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$280
This Southwest deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/227:00 am
ONT
- MDW
2 stops7h 00m
Southwest
Sat 9/261:15 pm
MDW
- ONT
1 stop7h 10m
Southwest
Deal found 8/1![Southwest logo]()
$294
This Alaska Airlines deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/193:14 pm
ONT
- ORD
1 stop13h 06m
Alaska Airlines
Mon 9/216:00 am
ORD
- ONT
2 stops12h 10m
Alaska Airlines
Deal found 7/31![Alaska Airlines logo]()
$435
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/108:00 am
ONT
- RFD
1 stop10h 39m
Multiple Airlines
Sun 9/139:29 pm
RFD
- ONT
1 stop15h 53m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$294
This Delta deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/1412:22 pm
ONT
- ORD
1 stop9h 37m
Delta
Thu 1/79:30 am
ORD
- ONT
2 stops8h 42m
Delta
Deal found 8/2![Delta logo]()
$294
This Southwest deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/1110:50 am
ONT
- MDW
Nonstop3h 45m
Southwest
Fri 11/138:55 am
MDW
- ONT
1 stop7h 10m
Southwest
Deal found 7/28![Southwest logo]()
$311
This United Airlines deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/137:00 am
ONT
- ORD
Nonstop4h 10m
United Airlines
Mon 11/164:15 pm
ORD
- ONT
Nonstop4h 32m
United Airlines
Deal found 8/1![United Airlines logo]()
$316
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1211:19 am
ONT
- RFD
1 stop6h 43m
Multiple Airlines
Sun 11/158:37 pm
RFD
- ONT
1 stop15h 47m
Multiple Airlines
Deal found 7/31![Multiple Airlines logo]()
$294
This Southwest deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/1012:30 pm
ONT
- MDW
1 stop8h 35m
Southwest
Fri 11/1310:45 am
MDW
- ONT
Nonstop4h 20m
Southwest
Deal found 7/28![Southwest logo]()
$311
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/172:30 pm
ONT
- RFD
2 stops25h 41m
Multiple Airlines
Sun 9/209:29 pm
RFD
- ONT
1 stop11h 35m
Multiple Airlines
Deal found 7/31![Multiple Airlines logo]()
$297
This Southwest deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/2911:55 pm
ONT
- MDW
Nonstop3h 45m
Southwest
Fri 11/610:15 am
MDW
- ONT
2 stops7h 10m
Southwest
Deal found 7/30![Southwest logo]()
$312
This Delta deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/296:01 pm
ONT
- MDW
2 stops12h 43m
Delta
Fri 11/610:01 am
MDW
- ONT
2 stops14h 42m
Delta
Deal found 8/1![Delta logo]()
$346
This United Airlines deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/281:52 pm
ONT
- ORD
1 stop9h 07m
United Airlines
Wed 9/308:20 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 7/29![United Airlines logo]()
$349
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/2011:15 am
ONT
- RFD
1 stop7h 30m
Multiple Airlines
Sun 8/239:35 pm
RFD
- ONT
1 stop12h 28m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$300
This United Airlines deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/241:18 pm
ONT
- ORD
1 stop8h 41m
United Airlines
Wed 9/28:06 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 7/29![United Airlines logo]()
$349
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/2911:19 am
ONT
- RFD
1 stop6h 11m
Multiple Airlines
Sun 11/81:08 pm
RFD
- ONT
2 stops50h 32m
Multiple Airlines
Deal found 7/30![Multiple Airlines logo]()
$315
This United Airlines deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/297:00 am
ONT
- ORD
Nonstop4h 10m
United Airlines
Sat 9/58:06 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 8/2![United Airlines logo]()
$356
This Delta deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/1812:00 pm
ONT
- MDW
1 stop8h 36m
Delta
Mon 8/2412:46 pm
MDW
- ONT
1 stop7h 44m
Delta
Deal found 7/31![Delta logo]()
$397
This Southwest deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/294:15 pm
ONT
- MDW
1 stop6h 55m
Southwest
Sun 11/810:15 am
MDW
- ONT
2 stops7h 10m
Southwest
Deal found 7/30![Southwest logo]()
$369
This Southwest deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/196:40 am
ONT
- MDW
2 stops8h 30m
Southwest
Sun 8/239:25 pm
MDW
- ONT
Nonstop4h 10m
Southwest
Deal found 7/29![Southwest logo]()
$373
This United Airlines deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/287:00 am
ONT
- ORD
Nonstop4h 10m
United Airlines
Fri 9/43:35 pm
ORD
- ONT
1 stop9h 24m
United Airlines
Deal found 7/30![United Airlines logo]()
$373
This Delta deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/316:01 pm
ONT
- MDW
2 stops12h 38m
Delta
Sat 9/59:24 am
MDW
- ONT
2 stops9h 00m
Delta
Deal found 7/28![Delta logo]()
$420
This Southwest deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/18:40 pm
ONT
- MDW
1 stop7h 05m
Southwest
Sat 11/76:05 am
MDW
- ONT
2 stops8h 45m
Southwest
Deal found 7/29![Southwest logo]()
$373
This United Airlines deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/291:18 pm
ONT
- ORD
1 stop6h 12m
United Airlines
Tue 9/18:06 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 7/31![United Airlines logo]()
$379
This Delta deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/2512:00 pm
ONT
- MDW
1 stop8h 36m
Delta
Sat 8/291:25 pm
MDW
- ONT
2 stops10h 58m
Delta
Deal found 7/28![Delta logo]()
$424
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/111:19 am
ONT
- RFD
1 stop6h 44m
Multiple Airlines
Sun 11/81:08 pm
RFD
- ONT
2 stops50h 32m
Multiple Airlines
Deal found 7/30![Multiple Airlines logo]()
$386
This United Airlines deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/241:24 pm
ONT
- ORD
1 stop8h 35m
United Airlines
Mon 9/288:20 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 8/2![United Airlines logo]()
$379
This Delta deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/139:45 am
ONT
- ORD
2 stops11h 49m
Delta
Tue 10/202:03 pm
ORD
- ONT
2 stops10h 40m
Delta
Deal found 8/1![Delta logo]()
$446
Last-minute flights from Ontario to ChicagoDiscover last-minute flight deals from Ontario to Chicago. Data last updated August 3, 2026 and is based on user searches.
Discover last-minute flight deals from Ontario to Chicago. Data last updated August 3, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/187:56 pm
ONT
- ORD
1 stop15h 40m
Frontier
Mon 8/317:05 am
ORD
- ONT
2 stops18h 45m
Frontier
Deal found 7/28![Frontier logo]()
$276
This Trip.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/189:37 am
ONT
- ORD
1 stop8h 38m
Frontier
Tue 9/156:30 am
ORD
- ONT
1 stop6h 00m
Frontier
Deal found 7/31![Frontier logo]()
$280
This CheapOair deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/203:40 pm
ONT
- ORD
1 stop25h 22m
Frontier
Mon 8/248:11 pm
ORD
- ONT
1 stop21h 43m
Frontier
Deal found 7/31![Frontier logo]()
$284
This Trip.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/218:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Mon 8/249:26 pm
MDW
- ONT
1 stop13h 10m
Frontier
Deal found 7/30![Frontier logo]()
$277
This Frontier deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/218:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/239:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/31![Frontier logo]()
$281
This Frontier deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/238:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Mon 8/319:26 pm
MDW
- ONT
1 stop13h 10m
Frontier
Deal found 7/29![Frontier logo]()
$279
This Frontier deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/238:17 am
ONT
- ORD
1 stop9h 58m
Frontier
Sat 8/298:45 am
ORD
- ONT
1 stop12h 16m
Frontier
Deal found 7/29![Frontier logo]()
$279
This Frontier deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/239:33 am
ONT
- ORD
1 stop13h 16m
Frontier
Fri 8/282:41 pm
ORD
- ONT
1 stop11h 09m
Frontier
Deal found 8/2![Frontier logo]()
$281
This Frontier deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/248:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/309:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/28![Frontier logo]()
$278
This United Airlines deal was found by Cheapflights users on 7/28. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/257:00 am
ONT
- ORD
Nonstop4h 10m
United Airlines
Tue 9/18:06 pm
ORD
- ONT
Nonstop4h 29m
United Airlines
Deal found 7/28![United Airlines logo]()
$278
This Frontier deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/288:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Sun 8/309:26 pm
MDW
- ONT
1 stop13h 12m
Frontier
Deal found 7/31![Frontier logo]()
$280
This Frontier deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/297:56 pm
ONT
- ORD
1 stop15h 40m
Frontier
Sat 9/58:45 am
ORD
- ONT
1 stop12h 16m
Frontier
Deal found 8/1![Frontier logo]()
$286
One-way flights from Ontario to ChicagoSearch for one-way flight options from Ontario to Chicago. Find affordable one-way fares based on user searches. Data last updated August 3, 2026.
Search for one-way flight options from Ontario to Chicago. Find affordable one-way fares based on user searches. Data last updated August 3, 2026.
This Super.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/218:24 pm
ONT
- ORD
1 stop7h 14m
Frontier
Deal found 7/31![Frontier logo]()
$79
This Frontier deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/278:17 am
ONT
- ORD
1 stop9h 58m
Frontier
Deal found 7/30![Frontier logo]()
$80
This Super.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/319:33 am
ONT
- ORD
1 stop13h 16m
Frontier
Deal found 7/30![Frontier logo]()
$85
This Frontier deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/278:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Deal found 7/30![Frontier logo]()
$86
This Booking.com deal was found by Cheapflights users on 7/30. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/249:33 am
ONT
- ORD
1 stop13h 16m
Frontier
Deal found 7/30![Frontier logo]()
$86
This Super.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/259:37 am
ONT
- ORD
1 stop8h 38m
Frontier
Deal found 7/31![Frontier logo]()
$94
This Frontier deal was found by Cheapflights users on 8/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/19:37 am
ONT
- ORD
1 stop8h 38m
Frontier
Deal found 8/1![Frontier logo]()
$95
This Trip.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/156:15 am
ONT
- ORD
1 stop16h 08m
Frontier
Deal found 7/29![Frontier logo]()
$98
This Super.com deal was found by Cheapflights users on 7/31. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/248:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Deal found 7/31![Frontier logo]()
$99
This Super.com deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/33:40 pm
ONT
- ORD
1 stop25h 22m
Frontier
Deal found 8/2![Frontier logo]()
$100
This Frontier deal was found by Cheapflights users on 8/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/318:17 am
ONT
- MDW
1 stop10h 14m
Frontier
Deal found 8/2![Frontier logo]()
$101
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/296:15 am
ONT
- ORD
1 stop16h 08m
Frontier
Deal found 7/29![Frontier logo]()
$101
Find flight deals from Ontario to Chicago
Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Chicago (CHI). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated August 3, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $276 (United Airlines) |
One-way from | $79 (Super.com) |
Popular in | December |
Cheapest in | January |
Average price | $397 |
Good round-trip deal | $378 or less |
Good one-way deal | $203 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Ontario to Chicago that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated August 3, 2026.
Use the filters below to find and compare flights from Ontario to Chicago that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
OntarioChicago
ONT - MDW
ONTMDW
Ontario
Sun 9/6
12:00 pm-10:36 pm
1 stop8h 36m
Chicago Midway
Tue 9/15
1:00 pm-11:47 pm
2 stops12h 47m
$279
OntarioChicago
ONT - ORD
ONTORD
Ontario
Sat 11/14
5:00 am-1:14 pm
1 stop6h 14m
Chicago O'Hare Intl
Mon 11/16
4:15 pm-6:47 pm
Nonstop4h 32m
$279
OntarioChicago
ONT - RFD
ONTRFD
Ontario
Thu 11/5
11:19 am-8:02 pm
1 stop6h 43m
Chicago Greater Rockford
Sun 11/8
1:08 pm-11:55 pm
2 stops36h 47m
$280
OntarioChicago
ONT - MDW
ONTMDW
Ontario
Tue 9/22
7:00 am-4:00 pm
2 stops7h 00m
Chicago Midway
Sat 9/26
1:15 pm-6:25 pm
1 stop7h 10m
$294
OntarioChicago
ONT - RFD
ONTRFD
Ontario
Thu 9/10
8:00 am-8:39 pm
1 stop10h 39m
Chicago Greater Rockford
Sun 9/13
9:29 pm-11:22 am
1 stop15h 53m
$294
OntarioChicago
ONT - ORD
ONTORD
Ontario
Mon 12/14
12:22 pm-11:59 pm
1 stop9h 37m
Chicago O'Hare Intl
Thu 1/7
9:30 am-4:12 pm
2 stops8h 42m
$294
OntarioChicago
ONT - RFD
ONTRFD
Ontario
Thu 11/12
11:19 am-8:02 pm
1 stop6h 43m
Chicago Greater Rockford
Sun 11/15
8:37 pm-10:24 am
1 stop15h 47m
$294
OntarioChicago
ONT - RFD
ONTRFD
Ontario
Thu 9/17
2:30 pm-6:11 pm
2 stops25h 41m
Chicago Greater Rockford
Sun 9/20
9:29 pm-7:04 am
1 stop11h 35m
$297
OntarioChicago
ONT - RFD
ONTRFD
Ontario
Thu 8/20
11:15 am-8:45 pm
1 stop7h 30m
Chicago Greater Rockford
Sun 8/23
9:35 pm-8:03 am
1 stop12h 28m
$300
OntarioChicago
ONT - MDW
ONTMDW
Ontario
Wed 11/11
10:50 am-4:35 pm
Nonstop3h 45m
Chicago Midway
Fri 11/13
8:55 am-2:05 pm
1 stop7h 10m
$311
Showing 1-10 of 57 resultsSorted by cheapest first
Compare providers for flights from Ontario to Chicago
Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to Chicago in August.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star |
- Most accurate provider: When it comes to deals on Ontario-Chicago flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-Chicago flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-Chicago flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Ontario-Chicago flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-Chicago flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.
Best time to book a flight from Ontario to Chicago
Have a flexible travel schedule? Discover the best time to fly to Chicago from Ontario with our price prediction graph.
ONT-CHI
ONT-MDW
ONT-ORD
ONT-RFD
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Ontario to Chicago
ONT-CHI
ONT-MDW
ONT-ORD
ONT-RFD
What is the cheapest month to book a flight from Ontario to Chicago?
Currently, January is the cheapest month in which you can book a flight from Ontario to Chicago (average of $345). Flying from Ontario to Chicago in December is currently the most expensive (average of $483). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
What is the cheapest time of day to fly from ONT to CHI?
Find hourly flight availability from Ontario to Chicago. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated August 3, 2026.
When flying from Ontario to Chicago, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
Weekly flight availability from Ontario to Chicago
Explore weekly flight availability from Ontario to Chicago. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated August 3, 2026.
The most flights from ONT to CHI are scheduled on a Friday (4 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (2 on average).
How much does it cost to fly round-trip from Ontario to Chicago?
Airfare is below average for this route at the moment.
Ontario to Chicago flights typically cost between $304 and $481 in August.The cheapest round-trip price found within the last 5 days was $276 on United Airlines (Aug 25-Aug 27).
How far ahead should I book a flight from Ontario to Chicago?
The best time to book flights from Ontario to Chicago is 75 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.
The best insider tips for Ontario to Chicago flights
AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Chicago trip
Our travel experts
Reviews of airlines servicing Chicago
Get insights into the airlines that provide service to Chicago. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Chicago. Reviews last updated August 3, 2026.
See what other customers who have flown with Southwest,Delta, andUnited Airlines from Ontario to Chicago have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Related info for your journey
Find useful and relevant information for your journey from Ontario to Chicago. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
Traveling to a place near Chicago?
Book flights to Chicago if you plan to visit one of these locationsBenton Harbor
Lansing
Merrillville
Valparaiso
Hammond
Saint Joseph
Porter
Browse thousands of different options on Cheapflights for your next trip
Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.
Alternative routes
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Alternative routes for Ontario to Chicago
See prices for flight routes from nearby airports that may be better suited for you.
Other flights to Chicago
Explore flights to Chicago departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on August 3, 2026.
Complete your trip
Complete your trip to Chicago by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Ontario to Chicago by cabin class
Find flights from Ontario to Chicago, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Ontario and Chicago flights
Browse other Ontario and Chicago flight options. Last updated on August 3, 2026.
Other flights from Ontario
Browse through other flights departing from Ontario. Flights are based on user searches made on Cheapflights and were last updated on August 3, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Top 5 airlines flying from Ontario to Chicago
Discover the top 5 airlines that operate flights from Ontario to Chicago. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated August 3, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$131 | Average$266 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$255 | Average$428 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$258 | Average$446 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$268 | Average$458 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$316 | Average$469 | FlexibilityNo cancel fee | On-time71% |