$108+ Cheap flights from Ontario to St. Louis (ONT - STL)
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 12/15. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — STL
Oct 17 — Oct 241
Round-trip
1 adult, Economy
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Find cheap flights from Ontario to St. Louis 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.Cheap flight deals from Ontario to St. Louis
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Best
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One-way
Cheapest flights from Ontario to St. LouisExplore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2026.
Explore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2026.
This Kiwi.com deal was found by Cheapflights users on 9/12. 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.
Wed 11/186:25 am -
1 stop6h 58m
Wed 12/27:49 pm -
1 stop22h 02m
Deal found 9/12![Frontier logo]()
$167
This Frontier deal was found by Cheapflights users on 9/16. 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.
Wed 10/216:15 am -
1 stop7h 09m
Wed 11/44:18 pm -
1 stop9h 33m
Deal found 9/16![Frontier logo]()
$208
This Booking.com deal was found by Cheapflights users on 9/16. 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.
Tue 10/2711:52 am -
1 stop25h 31m
Sat 10/317:59 pm -
1 stop5h 52m
Deal found 9/16![Frontier logo]()
$214
This Booking.com deal was found by Cheapflights users on 9/16. 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 10/52:30 pm -
1 stop19h 02m
Wed 10/78:10 pm -
1 stop5h 37m
Deal found 9/16![Frontier logo]()
$230
This Booking.com deal was found by Cheapflights users on 9/16. 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.
Wed 10/145:25 pm -
1 stop16h 06m
Mon 10/191:30 pm -
1 stop23h 01m
Deal found 9/16![Frontier logo]()
$236
This Frontier deal was found by Cheapflights users on 9/16. 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 10/166:15 am -
1 stop11h 00m
Fri 10/238:00 pm -
1 stop5h 50m
Deal found 9/16![Frontier logo]()
$240
This Frontier deal was found by Cheapflights users on 9/16. 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 10/2611:52 am -
1 stop5h 23m
Sat 10/317:59 pm -
1 stop5h 52m
Deal found 9/16![Frontier logo]()
$243
This Mytrip deal was found by Cheapflights users on 9/16. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/128:35 pm -
1 stop13h 58m
Sat 11/147:59 pm -
1 stop16h 36m
Deal found 9/16![Frontier logo]()
$251
This Trip.com deal was found by Cheapflights users on 9/16. 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.
Thu 10/158:35 pm -
1 stop14h 00m
Mon 10/191:30 pm -
1 stop23h 01m
Deal found 9/16![Frontier logo]()
$258
This Expedia deal was found by Cheapflights users on 9/16. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/306:25 am -
1 stop10h 49m
Mon 11/21:28 pm -
1 stop22h 12m
Deal found 9/16![Frontier logo]()
$260
This Southwest deal was found by Cheapflights users on 9/15. 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 10/204:15 pm -
1 stop5h 40m
Tue 10/276:20 am -
1 stop5h 25m
Deal found 9/15![Southwest logo]()
$267
Best flights from Ontario to St. LouisDiscover carefully curated flight deals from Ontario to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated September 17, 2026.
Discover carefully curated flight deals from Ontario to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated September 17, 2026.
This Delta deal was found by Cheapflights users on 9/15. 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 11/125:04 pm -
1 stop5h 36m
Sat 11/147:08 am -
1 stop7h 09m
Deal found 9/15![Delta logo]()
$290
This Southwest deal was found by Cheapflights users on 9/13. 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 11/188:40 am -
2 stops6h 45m
Thu 11/195:25 pm -
1 stop6h 20m
Deal found 9/13![Southwest logo]()
$362
This United Airlines deal was found by Cheapflights users on 9/12. 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 10/136:00 am -
1 stop6h 10m
Wed 10/141:29 pm -
2 stops11h 22m
Deal found 9/12![United Airlines logo]()
$401
This Delta deal was found by Cheapflights users on 9/15. 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 11/2612:18 pm -
1 stop8h 35m
Sat 12/127:08 am -
1 stop7h 09m
Deal found 9/15![Delta logo]()
$290
This Southwest deal was found by Cheapflights users on 9/14. 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 10/1311:55 pm -
1 stop8h 55m
Thu 10/155:05 am -
1 stop6h 20m
Deal found 9/14![Southwest logo]()
$394
This Southwest deal was found by Cheapflights users on 9/14. 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 12/69:00 am -
2 stops8h 50m
Thu 12/105:25 pm -
1 stop6h 15m
Deal found 9/14![Southwest logo]()
$412
This Delta deal was found by Cheapflights users on 9/15. 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.
Fri 11/135:04 pm -
1 stop5h 36m
Sun 11/157:00 pm -
1 stop6h 49m
Deal found 9/15![Delta logo]()
$423
This United Airlines deal was found by Cheapflights users on 9/15. 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.
Wed 1/131:00 pm -
1 stop5h 59m
Sun 1/173:00 pm -
1 stop7h 20m
Deal found 9/15![United Airlines logo]()
$477
This Southwest deal was found by Cheapflights users on 9/15. 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 11/193:20 pm -
1 stop5h 50m
Fri 11/205:45 am -
1 stop9h 20m
Deal found 9/15![Southwest logo]()
$421
This Delta deal was found by Cheapflights users on 9/16. 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.
Wed 11/2512:18 pm -
1 stop7h 24m
Fri 11/276:00 am -
1 stop7h 08m
Deal found 9/16![Delta logo]()
$426
This Southwest deal was found by Cheapflights users on 9/12. 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 11/188:55 am -
2 stops10h 10m
Sun 11/222:45 pm -
2 stops9h 10m
Deal found 9/12![Southwest logo]()
$442
Last-minute flights from Ontario to St. LouisDiscover last-minute flight deals from Ontario to St. Louis. Data last updated September 17, 2026 and is based on user searches.
Discover last-minute flight deals from Ontario to St. Louis. Data last updated September 17, 2026 and is based on user searches.
This Booking.com deal was found by Cheapflights users on 9/16. 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 10/52:30 pm -
1 stop19h 02m
Wed 10/78:10 pm -
1 stop5h 37m
Deal found 9/16![Frontier logo]()
$230
This Booking.com deal was found by Cheapflights users on 9/16. 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.
Wed 10/145:25 pm -
1 stop16h 06m
Mon 10/191:30 pm -
1 stop23h 01m
Deal found 9/16![Frontier logo]()
$236
This Trip.com deal was found by Cheapflights users on 9/16. 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.
Thu 10/158:35 pm -
1 stop14h 00m
Mon 10/191:30 pm -
1 stop23h 01m
Deal found 9/16![Frontier logo]()
$258
This Frontier deal was found by Cheapflights users on 9/16. 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 10/166:15 am -
1 stop11h 00m
Fri 10/238:00 pm -
1 stop5h 50m
Deal found 9/16![Frontier logo]()
$240
This Alaska Airlines deal was found by Cheapflights users on 9/15. 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 10/172:13 pm -
1 stop7h 46m
Thu 10/297:02 am -
1 stop8h 14m
Deal found 9/15![Alaska Airlines logo]()
$285
This Southwest deal was found by Cheapflights users on 9/15. 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 10/204:15 pm -
1 stop5h 40m
Tue 10/276:20 am -
1 stop5h 25m
Deal found 9/15![Southwest logo]()
$267
This Frontier deal was found by Cheapflights users on 9/16. 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.
Wed 10/216:15 am -
1 stop7h 09m
Wed 11/44:18 pm -
1 stop9h 33m
Deal found 9/16![Frontier logo]()
$208
This Frontier deal was found by Cheapflights users on 9/16. 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 10/2611:52 am -
1 stop5h 23m
Sat 10/317:59 pm -
1 stop5h 52m
Deal found 9/16![Frontier logo]()
$243
This Booking.com deal was found by Cheapflights users on 9/16. 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.
Tue 10/2711:52 am -
1 stop25h 31m
Sat 10/317:59 pm -
1 stop5h 52m
Deal found 9/16![Frontier logo]()
$214
This Gotogate deal was found by Cheapflights users on 9/15. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/2711:13 am -
1 stop10h 46m
Sat 10/316:02 am -
1 stop9h 14m
Deal found 9/15![Alaska Airlines logo]()
$279
This Expedia deal was found by Cheapflights users on 9/16. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/306:25 am -
1 stop10h 49m
Mon 11/21:28 pm -
1 stop22h 12m
Deal found 9/16![Frontier logo]()
$260
One-way flights from Ontario to St. LouisSearch for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated September 17, 2026.
Search for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated September 17, 2026.
This Super.com deal was found by Cheapflights users on 9/16. 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 12/156:00 am -
1 stop27h 04m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$108
This deal was found by Cheapflights users on 9/16. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/211:52 am -
1 stop5h 22m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$116
This Super.com deal was found by Cheapflights users on 9/16. 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.
Fri 10/2311:52 am -
1 stop5h 23m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$119
This Super.com deal was found by Cheapflights users on 9/16. 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 10/221:38 pm -
1 stop20h 57m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$124
This Expedia deal was found by Cheapflights users on 9/17. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/52:23 pm -
1 stop20h 10m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/17![Frontier logo]()
$126
This Kiwi.com deal was found by Cheapflights users on 9/14. 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 10/2710:35 am -
2 stops29h 05m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/14![Frontier logo]()
$128
This Alaska Airlines deal was found by Cheapflights users on 9/15. 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.
Tue 10/62:13 pm -
1 stop7h 46m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/15![Alaska Airlines logo]()
$134
This Super.com deal was found by Cheapflights users on 9/17. 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 10/2611:52 am -
1 stop5h 23m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/17![Frontier logo]()
$137
This Booking.com deal was found by Cheapflights users on 9/15. 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.
Wed 11/410:35 am -
1 stop23h 58m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/15![Frontier logo]()
$138
This Super.com deal was found by Cheapflights users on 9/16. 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 11/96:25 am -
1 stop10h 49m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$143
Find flight deals from Ontario to St. Louis
Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to St. Louis (STL). 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 September 17, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $167 (Kiwi.com) |
One-way from | $108 (Super.com) |
Popular in | July |
Cheapest in | April |
Average price | $300 |
Cheapflights Fare Finder
Customize your flight search to find flights from Ontario to St. Louis 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 7,457,451 searches. Data last updated September 17, 2026.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 10/21
2:13 pm-11:59 pm
1 stop7h 46m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$134
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Mon 11/2
11:55 pm-11:00 am
1 stop9h 05m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$152
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Fri 10/9
11:15 pm-9:42 am
1 stop8h 27m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$170
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Sat 1/16
7:00 am-4:53 pm
1 stop7h 53m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$179
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Tue 10/13
5:03 pm-12:44 am
1 stop5h 41m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$179
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 9/23
11:45 am-7:17 pm
1 stop5h 32m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$202
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Mon 12/21
6:27 pm-5:26 am
1 stop8h 59m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$202
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Sat 9/26
11:45 am-7:17 pm
1 stop5h 32m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$204
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Thu 12/31
1:38 pm-9:08 pm
1 stop5h 30m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$229
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Mon 11/9
6:25 am-5:40 pm
2 stops9h 15m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$251
Showing 1-10 of 22 resultsSorted by cheapest first
Compare providers for flights from Ontario to St. Louis
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 St. Louis in September.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star |
- Most accurate provider: When it comes to deals on Ontario-St. Louis flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-St. Louis flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Ontario-St. Louis 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-St. Louis 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 St. Louis
Have a flexible travel schedule? Discover the best time to fly to St. Louis from Ontario with our price prediction graph.
ONT-STL
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 St. Louis
What is the cheapest month to book a flight from Ontario to St. Louis?
Currently, April is the cheapest month in which you can book a flight from Ontario to St. Louis (average of $250). Flying from Ontario to St. Louis in July is currently the most expensive (average of $596). 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.
How much does it cost to fly round-trip from Ontario to St. Louis?
Airfare is below average for this route at the moment.
Ontario to St. Louis flights typically cost between $175 and $457 in November.The cheapest round-trip price found within the last 5 days was $167 on Frontier (Nov 18-Dec 2).
Reviews of airlines servicing St. Louis
Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated September 17, 2026.
Get a feel of what it's like to fly with Southwest,Delta, andUnited Airlines from Ontario to St. Louis by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Boarding
8.1
Entertainment
7.5
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Related info for your journey
Find useful and relevant information for your journey from Ontario to St. Louis. 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 St. Louis?
Book flights to St. Louis if you plan to visit one of these locationsFairview Heights
O'Fallon
Fenton
Swansea
Eureka
Maryland Heights
Collinsville
Wentzville
Edwardsville
Glencoe
Chesterfield
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Ontario and St. Louis flights
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Top 5 airlines flying from Ontario to St. Louis
Discover the top 5 airlines that operate flights from Ontario to St. Louis. 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 7,457,451 searches. Data last updated September 17, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$105 | Average$264 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$165 | Average$437 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$292 | Average$536 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$292 | Average$438 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$346 | Average$486 | FlexibilityNo cancel fee | On-time63% |