$83+ Cheap flights from Ontario to Denver (ONT - DEN)
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 7/7. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
Jul 15 — Jul 221
Round-trip
1 adult, Economy
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Find cheap flights from Ontario to Denver 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 Denver Intl are usually found in February or October, booked 69 days in advance, depart on a Thursday or Friday and return on a Wednesday
Cheap flight deals from Ontario to Denver
Cheapest
Best
Last-minute
One-way
Cheapest flights from Ontario to DenverExplore the most affordable flight options available from Ontario to Denver. 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 Ontario to Denver. 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.
Tue 9/156:00 am
ONT
- DEN
Nonstop2h 26m
Frontier
Sat 9/2610:34 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/14![Frontier logo]()
$129
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/303:34 pm
ONT
- DEN
1 stop8h 04m
Frontier
Wed 7/110:29 pm
DEN
- ONT
Nonstop2h 20m
Frontier
Deal found 6/10![Frontier logo]()
$140
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 7/211:38 pm
ONT
- DEN
1 stop13h 10m
Frontier
Tue 7/2810:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$141
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.
Wed 8/1910:50 am
ONT
- DEN
Nonstop2h 19m
Frontier
Mon 8/2410:29 pm
DEN
- ONT
Nonstop2h 20m
Frontier
Deal found 6/12![Frontier logo]()
$142
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 7/221:38 pm
ONT
- DEN
1 stop7h 03m
Frontier
Wed 7/2910:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$143
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 11/126:15 am
ONT
- DEN
Nonstop2h 26m
Frontier
Thu 11/1210:34 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/11![Frontier logo]()
$144
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 11/126:15 am
ONT
- DEN
Nonstop2h 26m
Frontier
Wed 11/1810:34 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/12![Frontier logo]()
$145
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.
Wed 9/21:27 pm
ONT
- DEN
1 stop19h 03m
Frontier
Tue 9/810:29 pm
DEN
- ONT
Nonstop2h 20m
Frontier
Deal found 6/13![Frontier logo]()
$147
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/156:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Tue 7/214:25 pm
DEN
- ONT
1 stop16h 38m
Frontier
Deal found 6/10![Frontier logo]()
$148
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 8/43:40 pm
ONT
- DEN
1 stop5h 01m
Frontier
Tue 8/1110:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/12![Frontier logo]()
$149
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 7/226:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Sat 7/2510:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$152
Best flights from Ontario to DenverDiscover carefully curated flight deals from Ontario to Denver 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 Ontario to Denver 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 10/38:25 am
ONT
- DEN
Nonstop2h 10m
Southwest
Tue 10/66:30 am
DEN
- ONT
2 stops6h 50m
Southwest
Deal found 6/13![Southwest logo]()
$205
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/46:00 am
ONT
- DEN
1 stop5h 04m
Delta
Mon 8/105:35 am
DEN
- ONT
1 stop4h 17m
Delta
Deal found 6/12![Delta logo]()
$223
This Alaska Airlines 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/125:52 pm
ONT
- DEN
1 stop19h 23m
Alaska Airlines
Sat 11/147:50 am
DEN
- ONT
2 stops11h 01m
Alaska Airlines
Deal found 6/12![Alaska Airlines logo]()
$359
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/56:00 am
ONT
- DEN
1 stop4h 55m
Delta
Mon 12/712:45 pm
DEN
- ONT
1 stop4h 27m
Delta
Deal found 6/14![Delta logo]()
$223
This United Airlines 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/306:00 am
ONT
- DEN
2 stops12h 30m
United Airlines
Wed 7/85:15 am
DEN
- ONT
1 stop7h 57m
United Airlines
Deal found 6/14![United Airlines logo]()
$457
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/65:05 pm
ONT
- DEN
1 stop4h 50m
Delta
Mon 8/105:35 am
DEN
- ONT
1 stop4h 17m
Delta
Deal found 6/14![Delta logo]()
$223
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/51:06 pm
ONT
- DEN
1 stop5h 55m
Delta
Mon 8/107:05 am
DEN
- ONT
1 stop6h 11m
Delta
Deal found 6/12![Delta logo]()
$223
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.
Wed 7/224:10 pm
ONT
- DEN
2 stops6h 00m
Southwest
Wed 7/298:00 am
DEN
- ONT
1 stop4h 30m
Southwest
Deal found 6/12![Southwest logo]()
$337
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.
Wed 7/154:10 pm
ONT
- DEN
2 stops6h 00m
Southwest
Tue 7/212:40 pm
DEN
- ONT
2 stops6h 35m
Southwest
Deal found 6/13![Southwest logo]()
$342
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/239:43 am
ONT
- DEN
1 stop4h 19m
Delta
Mon 8/316:28 pm
DEN
- ONT
1 stop4h 55m
Delta
Deal found 6/14![Delta logo]()
$357
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.
Thu 11/125:55 am
ONT
- DEN
1 stop5h 05m
Southwest
Thu 11/123:10 pm
DEN
- ONT
2 stops5h 45m
Southwest
Deal found 6/11![Southwest logo]()
$441
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/296:00 am
ONT
- DEN
1 stop4h 53m
Delta
Tue 7/75:40 am
DEN
- ONT
1 stop4h 07m
Delta
Deal found 6/10![Delta logo]()
$378
Last-minute flights from Ontario to DenverDiscover last-minute flight deals from Ontario to Denver. Data last updated June 15, 2026 and is based on user searches.
Discover last-minute flight deals from Ontario to Denver. 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.
Tue 7/76:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Mon 7/138:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/11![Frontier logo]()
$144
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.
Wed 7/86:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Tue 7/1410:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/13![Frontier logo]()
$148
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 7/143:40 pm
ONT
- DEN
1 stop5h 01m
Frontier
Wed 7/2210:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/11![Frontier logo]()
$158
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.
Wed 7/156:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Tue 7/218:45 am
DEN
- ONT
Nonstop2h 19m
Frontier
Deal found 6/14![Frontier logo]()
$150
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 7/211:38 pm
ONT
- DEN
1 stop13h 10m
Frontier
Tue 7/2810:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$141
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/221:38 pm
ONT
- DEN
1 stop7h 03m
Frontier
Wed 7/2910:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/11![Frontier logo]()
$140
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 7/226:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Tue 7/289:06 pm
DEN
- ONT
1 stop11h 26m
Frontier
Deal found 6/10![Frontier logo]()
$143
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 7/226:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Sat 7/2510:29 pm
DEN
- ONT
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$152
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/286:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Wed 8/510:00 am
DEN
- ONT
1 stop6h 14m
Frontier
Deal found 6/13![Frontier logo]()
$149
One-way flights from Ontario to DenverSearch for one-way flight options from Ontario to Denver. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
Search for one-way flight options from Ontario to Denver. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
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 7/75:45 pm
ONT
- DEN
1 stop4h 25m
Southwest
Deal found 6/11![Southwest logo]()
$83
This Trip.com 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/183:34 pm
ONT
- DEN
1 stop11h 24m
Frontier
Deal found 6/11![Frontier logo]()
$87
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.
Tue 7/75:00 am
ONT
- DEN
Nonstop2h 20m
United Airlines
Deal found 6/13![United Airlines logo]()
$89
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/193:34 pm
ONT
- DEN
1 stop8h 04m
Frontier
Deal found 6/11![Frontier logo]()
$92
This Kiwi.com 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/92:58 pm
ONT
- DEN
1 stop8h 17m
Frontier
Deal found 6/10![Frontier logo]()
$93
This Super.com 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/46:00 am
ONT
- DEN
Nonstop2h 24m
Frontier
Deal found 6/10![Frontier logo]()
$95
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.
Tue 8/1110:49 am
ONT
- DEN
Nonstop2h 21m
Frontier
Deal found 6/10![Frontier logo]()
$96
This Delta 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/86:00 am
ONT
- DEN
1 stop4h 47m
Delta
Deal found 6/10![Delta logo]()
$99
This Mytrip 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/72:55 pm
ONT
- DEN
Nonstop2h 22m
Frontier
Deal found 6/11![Frontier logo]()
$102
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.
Wed 7/84:10 pm
ONT
- DEN
2 stops6h 00m
Southwest
Deal found 6/12![Southwest logo]()
$104
Find flight deals from Ontario to Denver
Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Denver (DEN). 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 | $129 (Frontier) |
One-way from | $83 (Southwest) |
Popular in | June |
Cheapest in | February |
Average price | $291 |
Good round-trip deal | $278 or less |
Good one-way deal | $180 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Ontario to Denver 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 Ontario to Denver that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
Quickest round-trip
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Sat 10/3
8:25 am-11:35 am
Nonstop2h 10m
Denver Intl
Tue 10/6
6:30 am-12:20 pm
2 stops6h 50m
$205
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Tue 8/4
6:00 am-12:04 pm
1 stop5h 04m
Denver Intl
Mon 8/10
5:35 am-8:52 am
1 stop4h 17m
$223
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Sat 12/5
6:00 am-11:55 am
1 stop4h 55m
Denver Intl
Mon 12/7
12:45 pm-4:12 pm
1 stop4h 27m
$223
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Thu 8/6
5:05 pm-10:55 pm
1 stop4h 50m
Denver Intl
Mon 8/10
5:35 am-8:52 am
1 stop4h 17m
$223
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Wed 8/5
1:06 pm-8:01 pm
1 stop5h 55m
Denver Intl
Mon 8/10
7:05 am-12:16 pm
1 stop6h 11m
$223
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Wed 7/22
4:10 pm-11:10 pm
2 stops6h 00m
Denver Intl
Wed 7/29
8:00 am-11:30 am
1 stop4h 30m
$337
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Wed 7/15
4:10 pm-11:10 pm
2 stops6h 00m
Denver Intl
Tue 7/21
2:40 pm-8:15 pm
2 stops6h 35m
$342
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Sun 8/23
9:43 am-3:02 pm
1 stop4h 19m
Denver Intl
Mon 8/31
6:28 pm-10:23 pm
1 stop4h 55m
$357
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Thu 11/12
5:52 pm-2:15 pm
1 stop19h 23m
Denver Intl
Sat 11/14
7:50 am-5:51 pm
2 stops11h 01m
$359
OntarioDenver
ONT - DEN
ONTDEN
Ontario
Mon 6/29
6:00 am-11:53 am
1 stop4h 53m
Denver Intl
Tue 7/7
5:40 am-8:47 am
1 stop4h 07m
$378
Showing 1-10 of 24 resultsSorted by cheapest first
Compare providers for flights from Ontario to Denver
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 Denver in June.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*1 star | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars |
- Most accurate provider: When it comes to deals on Ontario-Denver flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-Denver flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-Denver flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Ontario-Denver 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-Denver 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 Denver
Have a flexible travel schedule? Discover the best time to fly to Denver from Ontario with our price prediction graph.
ONT-DEN
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 Denver
Prices
Airlines
How far ahead should I book a flight from Ontario to Denver?
The price you pay for your flight from Ontario to Denver may vary depending on when you book. For the best chance of a lower fare, look to book 68 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 Ontario to Denver?
Currently, February is the cheapest month in which you can book a flight from Ontario to Denver (average of $167). Flying from Ontario to Denver in June is currently the most expensive (average of $291). 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 DEN?
Find hourly flight availability from Ontario to Denver. 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.
It’s typically best to fly out from Ontario to Denver in the evening. Doing so could potentially save you 52% on the flight price compared to flying at noon, which is usually more expensive.
What is the cheapest day to fly from Ontario to Denver?
Use this chart to determine the cheapest time to fly round-trip from Ontario to Denver. Price data was last updated on June 8, 2026.
Travelers seeking maximum savings on their Ontario to Denver flight should consider departing on Saturday afternoons when fares are most often at their lowest. Monday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
The best insider tips for Ontario to Denver 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 Denver trip
Our travel experts
Reviews of airlines servicing Denver
Get insights into the airlines that provide service to Denver. 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 Denver. Reviews last updated June 15, 2026.
Read through reviews of airlines operating flights from Ontario to Denver, such as Southwest,United Airlines, andFrontier. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Crew
8.6
Entertainment
7.5
Comfort
8.0
Food
7.0
Overall
7.9
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Crew
8.6
Entertainment
7.5
Comfort
8.0
Food
7.0
Overall
7.9
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Crew
8.6
Entertainment
7.5
Comfort
8.0
Food
7.0
Overall
7.9
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Crew
8.6
Entertainment
7.5
Comfort
8.0
Food
7.0
Overall
7.9
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Related info for your journey
Find useful and relevant information for your journey from Ontario to Denver. 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 Denver?
Book flights to Denver if you plan to visit one of these locationsThornton
Black Hawk
Westminster
Lakewood
Centennial
Broomfield
Golden
Greeley
Fort Morgan
Lone Tree
Wheat Ridge
Silverthorne
Central City
Cripple Creek
Winter Park
Manitou Springs
Frisco
Englewood
Glendale
Evergreen
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Alternative routes for Ontario to Denver
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Complete your trip
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Other flights to Denver
Explore flights to Denver departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on June 15, 2026.
Search flights from Ontario to Denver by cabin class
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Ontario and Denver flights
Browse other Ontario and Denver flight options. Last updated on June 15, 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 June 15, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Top 3 airlines flying from Ontario to Denver
Discover the top 3 airlines that operate flights from Ontario to Denver. 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$62 | Average$170 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$157 | Average$299 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$157 | Average$285 | FlexibilityNo cancel fee | On-time69% |