$32+ Cheap flights from Denver to Ontario (DEN - ONT)
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 12/8. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ONT
Nov 18 — Nov 251
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 May or April, booked 49 days in advance, depart on a Tuesday or Wednesday and return on a Saturday
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 October 19, 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 October 19, 2026.
This Frontier deal was found by Cheapflights users on 10/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/69:17 am -
Nonstop2h 25m
Tue 11/1011:52 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$77
This Frontier deal was found by Cheapflights users on 10/17. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/28:55 pm -
Nonstop2h 25m
Thu 12/106:00 am -
Nonstop2h 24m
Deal found 10/17![Frontier logo]()
$82
This Frontier deal was found by Cheapflights users on 10/14. 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.
Fri 12/2510:55 pm -
Nonstop2h 25m
Fri 1/16:20 am -
Nonstop2h 24m
Deal found 10/14![Frontier logo]()
$88
This Mytrip deal was found by Cheapflights users on 10/14. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/510:29 pm -
Nonstop2h 22m
Thu 11/126:30 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$90
This Frontier deal was found by Cheapflights users on 10/14. 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.
Fri 12/2510:55 pm -
Nonstop2h 25m
Tue 12/296:20 am -
Nonstop2h 24m
Deal found 10/14![Frontier logo]()
$92
This Frontier deal was found by Cheapflights users on 10/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/59:10 am -
Nonstop2h 25m
Sat 11/711:52 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$95
This Cheapflightsfares deal was found by Cheapflights users on 10/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/910:29 pm -
Nonstop2h 22m
Thu 11/126:30 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$99
This Cheapflightsfares deal was found by Cheapflights users on 10/14. 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.
Thu 12/1710:55 pm -
Nonstop2h 25m
Sun 12/206:20 am -
Nonstop2h 24m
Deal found 10/14![Frontier logo]()
$100
This Cheapflightsfares deal was found by Cheapflights users on 10/14. 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.
Mon 11/2310:52 pm -
Nonstop2h 22m
Thu 11/266:45 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$101
This Super.com deal was found by Cheapflights users on 10/14. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/49:10 am -
Nonstop2h 25m
Wed 11/1111:52 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$103
This Cheapflightsfares deal was found by Cheapflights users on 10/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/27:46 am -
1 stop16h 12m
Sat 12/56:00 am -
Nonstop2h 24m
Deal found 10/16![Frontier logo]()
$105
This Cheapflightsfares deal was found by Cheapflights users on 10/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/39:20 am -
Nonstop2h 25m
Fri 12/112:41 pm -
1 stop20h 12m
Deal found 10/16![Frontier logo]()
$106
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 October 19, 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 October 19, 2026.
This Delta deal was found by Cheapflights users on 10/14. 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 12/510:45 am -
1 stop6h 43m
Mon 12/75:04 pm -
1 stop5h 10m
Deal found 10/14![Delta logo]()
$198
This Southwest deal was found by Cheapflights users on 10/14. 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.
Thu 11/56:30 pm -
Nonstop2h 20m
Mon 11/96:30 am -
Nonstop2h 15m
Deal found 10/14![Southwest logo]()
$320
This United Airlines deal was found by Cheapflights users on 10/14. 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 11/1011:20 am -
1 stop5h 13m
Tue 11/174:17 pm -
1 stop6h 42m
Deal found 10/14![United Airlines logo]()
$337
This Alaska Airlines deal was found by Cheapflights users on 10/16. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 1/137:47 am -
2 stops15h 54m
Sat 1/167:10 am -
1 stop5h 57m
Deal found 10/16![Alaska Airlines logo]()
$362
This Delta deal was found by Cheapflights users on 10/15. 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.
Sat 1/96:25 pm -
1 stop5h 23m
Wed 1/205:05 pm -
1 stop4h 28m
Deal found 10/15![Delta logo]()
$293
This Southwest deal was found by Cheapflights users on 10/18. 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 12/58:40 am -
Nonstop2h 25m
Wed 12/91:55 pm -
Nonstop2h 10m
Deal found 10/18![Southwest logo]()
$330
This United Airlines deal was found by Cheapflights users on 10/16. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/37:45 pm -
Nonstop2h 26m
Mon 12/75:00 am -
Nonstop2h 17m
Deal found 10/16![United Airlines logo]()
$362
This Alaska Airlines deal was found by Cheapflights users on 10/16. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/97:03 am -
1 stop9h 10m
Sat 11/144:09 pm -
2 stops21h 18m
Deal found 10/16![Alaska Airlines logo]()
$417
This Delta deal was found by Cheapflights users on 10/15. 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.
Wed 1/612:45 pm -
1 stop4h 27m
Thu 1/146:00 am -
1 stop4h 55m
Deal found 10/15![Delta logo]()
$386
This Delta deal was found by Cheapflights users on 10/15. 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.
Wed 11/410:45 am -
1 stop6h 38m
Sat 11/71:35 pm -
1 stop4h 59m
Deal found 10/15![Delta logo]()
$461
This Alaska Airlines deal was found by Cheapflights users on 10/15. 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.
Fri 12/1811:49 am -
2 stops9h 14m
Sun 12/208:59 pm -
1 stop13h 18m
Deal found 10/15![Alaska Airlines logo]()
$527
This Delta deal was found by Cheapflights users on 10/17. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/56:00 am -
1 stop12h 15m
Thu 12/107:00 am -
1 stop9h 40m
Deal found 10/17![Delta logo]()
$523
Last-minute flights from Denver to OntarioDiscover last-minute flight deals from Denver to Ontario. Data last updated October 19, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Ontario. Data last updated October 19, 2026 and is based on user searches.
This Cheapflightsfares deal was found by Cheapflights users on 10/14. 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.
Wed 11/410:29 pm -
1 stop22h 01m
Sat 11/711:52 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$106
This Orbitz deal was found by Cheapflights users on 10/14. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/510:29 pm -
Nonstop2h 22m
Mon 11/96:30 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$90
This Frontier deal was found by Cheapflights users on 10/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/59:10 am -
Nonstop2h 25m
Sat 11/711:52 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$95
This Frontier deal was found by Cheapflights users on 10/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/69:17 am -
Nonstop2h 25m
Tue 11/1011:52 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$77
This Cheapflightsfares deal was found by Cheapflights users on 10/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/79:17 am -
Nonstop2h 25m
Mon 11/96:30 am -
Nonstop2h 21m
Deal found 10/16![Frontier logo]()
$103
This Cheapflightsfares deal was found by Cheapflights users on 10/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/910:29 pm -
Nonstop2h 22m
Thu 11/126:30 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$99
This Booking.com deal was found by Cheapflights users on 10/15. 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.
Mon 11/910:29 pm -
Nonstop2h 22m
Sat 11/146:30 am -
Nonstop2h 21m
Deal found 10/15![Frontier logo]()
$105
This Frontier deal was found by Cheapflights users on 10/16. 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.
Tue 11/1010:29 pm -
Nonstop2h 22m
Fri 11/1311:52 am -
Nonstop2h 21m
Deal found 10/16![Frontier logo]()
$82
This Cheapflightsfares deal was found by Cheapflights users on 10/14. 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.
Fri 11/139:17 am -
Nonstop2h 25m
Tue 11/176:30 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$88
This Cheapflightsfares deal was found by Cheapflights users on 10/19. 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.
Fri 11/139:17 am -
Nonstop2h 25m
Mon 11/166:30 am -
Nonstop2h 21m
Deal found 10/19![Frontier logo]()
$97
This Cheapflightsfares deal was found by Cheapflights users on 10/14. 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.
Mon 11/2310:52 pm -
Nonstop2h 22m
Thu 11/266:45 am -
Nonstop2h 21m
Deal found 10/14![Frontier logo]()
$101
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 October 19, 2026.
Search for one-way flight options from Denver to Ontario. Find affordable one-way fares based on user searches. Data last updated October 19, 2026.
This Kiwi.com deal was found by Cheapflights users on 10/15. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/89:20 am -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$32
This Cheapflightsfares deal was found by Cheapflights users on 10/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/49:10 am -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/16![Frontier logo]()
$33
This Cheapflightsfares deal was found by Cheapflights users on 10/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/1710:55 pm -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$34
This Cheapflightsfares deal was found by Cheapflights users on 10/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/510:29 pm -
Nonstop2h 22m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$44
This Trip.com deal was found by Cheapflights users on 10/16. 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.
Tue 1/1210:40 pm -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/16![Frontier logo]()
$48
This Super.com deal was found by Cheapflights users on 10/15. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 1/510:50 pm -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$53
This Cheapflightsfares deal was found by Cheapflights users on 10/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/310:55 pm -
Nonstop2h 22m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/16![Frontier logo]()
$54
This iWofly deal was found by Cheapflights users on 10/15. 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 iWofly is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/18:55 pm -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$63
This Super.com deal was found by Cheapflights users on 10/15. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/29:20 am -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/15![Frontier logo]()
$65
This CheapOair deal was found by Cheapflights users on 10/17. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/229:20 am -
Nonstop2h 25m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/17![Frontier logo]()
$70
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 October 19, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $77 (Frontier) |
One-way from | $32 (Kiwi.com) |
Popular in | June |
Cheapest in | May |
Average price | $207 |
Good round-trip deal | $152 or less |
Good one-way deal | $175 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 7,457,451 searches. Data last updated October 19, 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
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Sat 1/16
2:55 pm-8:02 pm
1 stop6h 07m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$89
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Tue 11/17
6:50 am-12:10 pm
1 stop6h 20m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$89
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Tue 11/24
10:52 pm-12:14 am
Nonstop2h 22m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$91
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Thu 12/3
5:19 pm-10:58 pm
1 stop6h 39m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$119
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Thu 12/24
8:50 am-2:30 pm
2 stops6h 40m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$131
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Thu 11/19
8:10 am-12:17 pm
1 stop5h 07m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$147
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Thu 11/5
7:25 pm-8:51 pm
Nonstop2h 26m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$159
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Sun 11/22
7:25 pm-8:51 pm
Nonstop2h 26m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$166
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Sat 12/5
10:45 am-4:28 pm
1 stop6h 43m
Ontario
Mon 12/7
5:04 pm-11:14 pm
1 stop5h 10m
$198
DenverOntario
DEN Denver Intl - ONT Ontario
DENONT
Denver Intl
Sat 11/14
7:33 am-3:13 pm
2 stops8h 40m
Ontario
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$227
Showing 1-10 of 23 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 October.
| 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*1 star | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*3 stars | |
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star | |
| Price Accuracy1 star | Trust Score*3 stars |
- 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.
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Everything you need to know about your flight from Denver to Ontario
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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 48 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, May is the cheapest month in which you can book a flight from Denver to Ontario (average of $176). Flying from Denver to Ontario in June is currently the most expensive (average of $290). 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 October 19, 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 31% 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 October 17, 2026.
Travelers seeking maximum savings on their Denver to Ontario flight should consider departing on Saturday evenings 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 October 19, 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.
Food
7.0
Overall
7.9
Comfort
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Food
7.0
Overall
7.9
Comfort
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Food
7.0
Overall
7.9
Comfort
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Food
7.0
Overall
7.9
Comfort
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
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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Alternative routes for Denver to Ontario
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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 October 19, 2026.
Denver and Ontario flights
Browse other Denver and Ontario flight options. Last updated on October 19, 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 October 19, 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 7,457,451 searches. Data last updated October 19, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$64 | Average$201 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$145 | Average$318 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$175 | Average$319 | FlexibilityNo cancel fee | On-time63% |