$27+ Cheap flights from Denver to Ontario (DEN - ONT)
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 7/29. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ONT
Jul 15 — Jul 221
Round-trip
1 adult, Economy
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Find cheap flights from Denver to Ontario 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 Denver Intl to Ontario are usually found in August or May, booked 84 days in advance, depart on a Wednesday or Saturday and return on a Thursday
Cheap flight deals from Denver to Ontario
Cheapest
Best
Last-minute
One-way
Cheapest flights from Denver to OntarioExplore the most affordable flight options available from Denver to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 15, 2026.
Explore the most affordable flight options available from Denver to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 15, 2026.
This Frontier deal was found by Cheapflights users on 6/14. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/208:44 am
DEN
- ONT
Nonstop2h 21m
Frontier
Sun 8/236:00 am
ONT
- DEN
Nonstop2h 26m
Frontier
Deal found 6/14![Frontier logo]()
$111
This Cheapflightsfares deal was found by Cheapflights users on 6/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/138:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Sat 8/156:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/13![Frontier logo]()
$112
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/410:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Sat 8/86:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/14![Frontier logo]()
$114
This Frontier deal was found by Cheapflights users on 6/12. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/610:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Mon 8/106:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/12![Frontier logo]()
$116
This Kiwi.com deal was found by Cheapflights users on 6/12. 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.
Tue 7/1410:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Tue 7/216:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/12![Frontier logo]()
$119
This Frontier deal was found by Cheapflights users on 6/12. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/2810:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Thu 8/206:00 am
ONT
- DEN
Nonstop2h 26m
Frontier
Deal found 6/12![Frontier logo]()
$121
This Frontier deal was found by Cheapflights users on 6/11. 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 7/410:29 pm
DEN
- ONT
Nonstop2h 20m
Frontier
Thu 7/96:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/11![Frontier logo]()
$122
This Frontier deal was found by Cheapflights users on 6/10. 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 7/298:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Tue 8/46:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/10![Frontier logo]()
$124
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/1912:32 pm
DEN
- ONT
Nonstop2h 25m
Frontier
Mon 9/212:55 pm
ONT
- DEN
Nonstop2h 22m
Frontier
Deal found 6/14![Frontier logo]()
$127
This Cheapflightsfares deal was found by Cheapflights users on 6/10. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/209:15 am
DEN
- ONT
Nonstop2h 28m
Frontier
Wed 10/284:27 pm
ONT
- DEN
1 stop6h 48m
Frontier
Deal found 6/10![Frontier logo]()
$131
This Priceline deal was found by Cheapflights users on 6/11. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/2310:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Mon 7/276:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/11![Frontier logo]()
$132
This Frontier deal was found by Cheapflights users on 6/10. 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 7/298:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Wed 8/59:36 am
ONT
- DEN
1 stop9h 27m
Frontier
Deal found 6/10![Frontier logo]()
$133
Best flights from Denver to OntarioDiscover carefully curated flight deals from Denver to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 15, 2026.
Discover carefully curated flight deals from Denver to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 15, 2026.
This Southwest deal was found by Cheapflights users on 6/13. 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.
Sat 8/89:05 am
DEN
- ONT
Nonstop2h 15m
Southwest
Mon 8/1012:25 pm
ONT
- DEN
Nonstop2h 10m
Southwest
Deal found 6/13![Southwest logo]()
$203
This United Airlines deal was found by Cheapflights users on 6/11. 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 7/1411:25 am
DEN
- ONT
Nonstop2h 22m
United Airlines
Tue 7/215:00 am
ONT
- DEN
Nonstop2h 20m
United Airlines
Deal found 6/11![United Airlines logo]()
$376
This Delta deal was found by Cheapflights users on 6/11. 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 7/265:40 am
DEN
- ONT
1 stop4h 07m
Delta
Sat 8/11:00 pm
ONT
- DEN
1 stop6h 01m
Delta
Deal found 6/11![Delta logo]()
$491
This Southwest deal was found by Cheapflights users on 6/10. 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 7/158:55 pm
DEN
- ONT
Nonstop2h 25m
Southwest
Tue 7/217:20 pm
ONT
- DEN
1 stop4h 00m
Southwest
Deal found 6/10![Southwest logo]()
$306
This Southwest deal was found by Cheapflights users on 6/10. 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.
Sat 7/187:55 am
DEN
- ONT
2 stops8h 20m
Southwest
Tue 7/217:20 pm
ONT
- DEN
1 stop4h 00m
Southwest
Deal found 6/10![Southwest logo]()
$333
This Southwest deal was found by Cheapflights users on 6/12. 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.
Tue 7/213:35 pm
DEN
- ONT
1 stop5h 45m
Southwest
Sat 7/255:40 am
ONT
- DEN
2 stops7h 10m
Southwest
Deal found 6/12![Southwest logo]()
$349
This United Airlines deal was found by Cheapflights users on 6/13. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/211:30 pm
DEN
- ONT
1 stop5h 41m
United Airlines
Mon 8/245:00 am
ONT
- DEN
Nonstop2h 21m
United Airlines
Deal found 6/13![United Airlines logo]()
$427
This Southwest deal was found by Cheapflights users on 6/13. 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.
Tue 7/146:25 pm
DEN
- ONT
1 stop5h 40m
Southwest
Sat 7/189:20 am
ONT
- DEN
2 stops6h 40m
Southwest
Deal found 6/13![Southwest logo]()
$349
This Delta deal was found by Cheapflights users on 6/11. 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 7/265:40 am
DEN
- ONT
1 stop4h 07m
Delta
Mon 8/31:06 pm
ONT
- DEN
1 stop5h 55m
Delta
Deal found 6/11![Delta logo]()
$491
This Southwest deal was found by Cheapflights users on 6/10. 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 7/29:15 pm
DEN
- ONT
Nonstop2h 20m
Southwest
Sun 7/511:55 am
ONT
- DEN
Nonstop2h 15m
Southwest
Deal found 6/10![Southwest logo]()
$471
Last-minute flights from Denver to OntarioDiscover last-minute flight deals from Denver to Ontario. Data last updated June 15, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Ontario. Data last updated June 15, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 6/11. 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 7/28:44 am
DEN
- ONT
Nonstop2h 21m
Frontier
Tue 7/76:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/11![Frontier logo]()
$144
This Frontier deal was found by Cheapflights users on 6/11. 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 7/410:29 pm
DEN
- ONT
Nonstop2h 20m
Frontier
Thu 7/96:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/11![Frontier logo]()
$122
This Kiwi.com deal was found by Cheapflights users on 6/12. 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.
Tue 7/1410:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Tue 7/216:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/12![Frontier logo]()
$119
This Priceline deal was found by Cheapflights users on 6/11. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/2310:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Mon 7/276:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/11![Frontier logo]()
$132
This Frontier deal was found by Cheapflights users on 6/12. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/2810:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Thu 8/206:00 am
ONT
- DEN
Nonstop2h 26m
Frontier
Deal found 6/12![Frontier logo]()
$121
This Frontier deal was found by Cheapflights users on 6/11. 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 7/288:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Wed 8/1210:49 am
ONT
- DEN
Nonstop2h 21m
Frontier
Deal found 6/11![Frontier logo]()
$139
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/288:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Tue 8/41:38 pm
ONT
- DEN
1 stop13h 12m
Frontier
Deal found 6/14![Frontier logo]()
$147
This Frontier deal was found by Cheapflights users on 6/10. 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 7/298:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Tue 8/46:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/10![Frontier logo]()
$124
This Frontier deal was found by Cheapflights users on 6/10. 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 7/298:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Wed 8/59:36 am
ONT
- DEN
1 stop9h 27m
Frontier
Deal found 6/10![Frontier logo]()
$133
This Frontier deal was found by Cheapflights users on 6/11. 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 7/2910:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Tue 8/118:17 am
ONT
- DEN
1 stop13h 38m
Frontier
Deal found 6/11![Frontier logo]()
$134
One-way flights from Denver to OntarioSearch for one-way flight options from Denver to Ontario. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
Search for one-way flight options from Denver to Ontario. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
This iWofly deal was found by Cheapflights users on 6/11. 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 iWofly is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/298:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/11![Frontier logo]()
$27
This Cheapflightsfares deal was found by Cheapflights users on 6/10. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/158:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/10![Frontier logo]()
$43
This Cheapflightsfares deal was found by Cheapflights users on 6/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/218:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/12![Frontier logo]()
$44
This Trip.com deal was found by Cheapflights users on 6/12. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/1410:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/12![Frontier logo]()
$46
This Cheapflightsfares deal was found by Cheapflights users on 6/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/98:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/14![Frontier logo]()
$54
This Cheapflightsfares deal was found by Cheapflights users on 6/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/58:44 am
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/13![Frontier logo]()
$57
This Cheapflightsfares deal was found by Cheapflights users on 6/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/610:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/12![Frontier logo]()
$59
This Cheapflightsfares deal was found by Cheapflights users on 6/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/78:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/13![Frontier logo]()
$61
This Cheapflightsfares deal was found by Cheapflights users on 6/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/288:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/12![Frontier logo]()
$64
This Cheapflightsfares deal was found by Cheapflights users on 6/13. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/1710:34 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/13![Frontier logo]()
$72
This Southwest deal was found by Cheapflights users on 6/11. 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 7/215:40 pm
DEN
- ONT
Nonstop2h 20m
Southwest
Deal found 6/11![Southwest logo]()
$73
Find flight deals from Denver to Ontario
Discover tips and strategies to find the most affordable flight options for your journey from Denver (DEN) to Ontario (ONT). 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 June 15, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $111 (Frontier) |
One-way from | $27 (iWofly) |
Popular in | March |
Cheapest in | August |
Average price | $260 |
Good round-trip deal | $189 or less |
Good one-way deal | $145 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Denver to Ontario 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 June 15, 2026.
Use the filters below to find and compare flights from Denver to Ontario that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
Quickest round-trip
DenverOntario
DEN - ONT
DENONT
Denver Intl
Sat 8/8
9:05 am-10:20 am
Nonstop2h 15m
Ontario
Mon 8/10
12:25 pm-3:35 pm
Nonstop2h 10m
$203
DenverOntario
DEN - ONT
DENONT
Denver Intl
Wed 7/15
8:55 pm-10:20 pm
Nonstop2h 25m
Ontario
Tue 7/21
7:20 pm-12:20 am
1 stop4h 00m
$306
DenverOntario
DEN - ONT
DENONT
Denver Intl
Sat 7/18
7:55 am-3:15 pm
2 stops8h 20m
Ontario
Tue 7/21
7:20 pm-12:20 am
1 stop4h 00m
$333
DenverOntario
DEN - ONT
DENONT
Denver Intl
Tue 7/21
3:35 pm-8:20 pm
1 stop5h 45m
Ontario
Sat 7/25
5:40 am-1:50 pm
2 stops7h 10m
$349
DenverOntario
DEN - ONT
DENONT
Denver Intl
Tue 7/14
6:25 pm-11:05 pm
1 stop5h 40m
Ontario
Sat 7/18
9:20 am-5:00 pm
2 stops6h 40m
$349
DenverOntario
DEN - ONT
DENONT
Denver Intl
Tue 7/14
11:25 am-12:47 pm
Nonstop2h 22m
Ontario
Tue 7/21
5:00 am-8:20 am
Nonstop2h 20m
$376
DenverOntario
DEN - ONT
DENONT
Denver Intl
Fri 8/21
1:30 pm-6:11 pm
1 stop5h 41m
Ontario
Mon 8/24
5:00 am-8:21 am
Nonstop2h 21m
$427
DenverOntario
DEN - ONT
DENONT
Denver Intl
Thu 7/2
9:15 pm-10:35 pm
Nonstop2h 20m
Ontario
Sun 7/5
11:55 am-3:10 pm
Nonstop2h 15m
$471
DenverOntario
DEN - ONT
DENONT
Denver Intl
Sun 7/26
5:40 am-8:47 am
1 stop4h 07m
Ontario
Sat 8/1
1:00 pm-8:01 pm
1 stop6h 01m
$491
DenverOntario
DEN - ONT
DENONT
Denver Intl
Sun 7/26
5:40 am-8:47 am
1 stop4h 07m
Ontario
Mon 8/3
1:06 pm-8:01 pm
1 stop5h 55m
$491
Showing 1-10 of 21 resultsSorted by cheapest first
Compare providers for flights from Denver to Ontario
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 Denver to Ontario in June.
| 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 | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*1 star | |
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | 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 Denver-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Denver-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Denver-Ontario flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Denver-Ontario 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 Denver-Ontario 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 Denver to Ontario
Have a flexible travel schedule? Discover the best time to fly to Ontario from Denver with our price prediction graph.
DEN-ONT
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 Denver to Ontario
Prices
Airlines
How far ahead should I book a flight from Denver to Ontario?
The price you pay for your flight from Denver to Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 83 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
What is the cheapest month to book a flight from Denver to Ontario?
Currently, August is the cheapest month in which you can book a flight from Denver to Ontario (average of $139). Flying from Denver to Ontario in March is currently the most expensive (average of $266). 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 DEN to ONT?
Find hourly flight availability from Denver to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 15, 2026.
One of the essential ways to save on airfare from Denver to Ontario is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the evening could potentially save you up to 21% on airfare.
What is the cheapest day to fly from Denver to Ontario?
Use this chart to determine the cheapest time to fly round-trip from Denver to Ontario. Price data was last updated on June 13, 2026.
Travelers seeking maximum savings on their Denver to Ontario flight should consider departing on Wednesday afternoons when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
The best insider tips for Denver to Ontario 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 Denver to Ontario trip
Our travel experts
Reviews of airlines servicing Ontario
Get insights into the airlines that provide service to Ontario. 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 Ontario. Reviews last updated June 15, 2026.
Read reviews from past customers who have flown Southwest,United Airlines, andFrontier from Denver to Ontario. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Entertainment
7.5
Comfort
8.0
Food
7.0
Crew
8.6
Boarding
8.1
Overall
7.9
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Comfort
8.0
Food
7.0
Crew
8.6
Boarding
8.1
Overall
7.9
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Comfort
8.0
Food
7.0
Crew
8.6
Boarding
8.1
Overall
7.9
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Entertainment
7.5
Comfort
8.0
Food
7.0
Crew
8.6
Boarding
8.1
Overall
7.9
Reviews
1 / 20
10.0
ExcellentWalter,May 2026
LAS - BUR
Related info for your journey
Find useful and relevant information for your journey from Denver to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Complete your trip
Complete your trip to Ontario by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Denver to Ontario by cabin class
Find flights from Denver to Ontario, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Other flights to Ontario
Explore flights to Ontario departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on June 15, 2026.
Denver and Ontario flights
Browse other Denver and Ontario flight options. Last updated on June 15, 2026.
Other flights from Denver
Browse through other flights departing from Denver. Flights are based on user searches made on Cheapflights and were last updated on June 15, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Top 3 airlines flying from Denver to Ontario
Discover the top 3 airlines that operate flights from Denver to Ontario. 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 June 15, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$64 | Average$177 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$131 | Average$301 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$157 | Average$289 | FlexibilityNo cancel fee | On-time63% |