$54 Cheap Flights from Denver (DEN) to Ontario (ONT)

View $54 flight on Wed, May 14, 2025Opens in a new window

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Find available prices by choosing your travel dates.

Cheap Flights from Denver to Ontario (DEN-ONT)

Prices were available within the past 7 days and start at $54 for one-way flights and $103 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Tue, May 6 - Wed, May 7
DEN
Denver
ONT
Ontario
$103 Roundtrip, just found
$103
Roundtrip
just found
Select Frontier Airlines flight, departing Tue, May 6 from Denver to Ontario, returning Wed, May 7, priced at $103 just found
Frontier Airlines
Sat, May 3 - Tue, May 6
DEN
Denver
ONT
Ontario
$108 Roundtrip, just found
$108
Roundtrip
just found
Select Frontier Airlines flight, departing Sat, May 3 from Denver to Ontario, returning Tue, May 6, priced at $108 just found
Frontier Airlines
Sat, May 10 - Sun, May 11
DEN
Denver
ONT
Ontario
$118 Roundtrip, found 2 hours ago
$118
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Sat, May 10 from Denver to Ontario, returning Sun, May 11, priced at $118 found 2 hours ago
Frontier Airlines
Sat, May 17 - Sat, May 24
DEN
Denver
ONT
Ontario
$118 Roundtrip, just found
$118
Roundtrip
just found
Select Frontier Airlines flight, departing Sat, May 17 from Denver to Ontario, returning Sat, May 24, priced at $118 just found
Frontier Airlines
Tue, May 13 - Wed, May 14
DEN
Denver
ONT
Ontario
$121 Roundtrip, found 8 hours ago
$121
Roundtrip
found 8 hours ago
Select Frontier Airlines flight, departing Tue, May 13 from Denver to Ontario, returning Wed, May 14, priced at $121 found 8 hours ago
Frontier Airlines
Sat, May 10 - Tue, May 20
DEN
Denver
ONT
Ontario
$123 Roundtrip, found 2 hours ago
$123
Roundtrip
found 2 hours ago
Select Frontier Airlines flight, departing Sat, May 10 from Denver to Ontario, returning Tue, May 20, priced at $123 found 2 hours ago
Southwest Airlines
Thu, May 15 - Sat, May 17
DEN
Denver
ONT
Ontario
$133 Roundtrip, found 19 hours ago
$133
Roundtrip
found 19 hours ago
Select Southwest Airlines flight, departing Thu, May 15 from Denver to Ontario, returning Sat, May 17, priced at $133 found 19 hours ago
United
Thu, May 15 - Sat, May 17
DEN
Denver
ONT
Ontario
$141 Roundtrip, found 19 hours ago
$141
Roundtrip
found 19 hours ago
Select United flight, departing Thu, May 15 from Denver to Ontario, returning Sat, May 17, priced at $141 found 19 hours ago
American Airlines
Tue, May 20 - Sat, May 24
DEN
Denver
ONT
Ontario
$199 Roundtrip, found 3 hours ago
$199
Roundtrip
found 3 hours ago
Select American Airlines flight, departing Tue, May 20 from Denver to Ontario, returning Sat, May 24, priced at $199 found 3 hours ago
Alaska Airlines
Wed, May 28 - Wed, Jun 4
DEN
Denver
ONT
Ontario
$216 Roundtrip, found 8 hours ago
$216
Roundtrip
found 8 hours ago
Select Alaska Airlines flight, departing Wed, May 28 from Denver to Ontario, returning Wed, Jun 4, priced at $216 found 8 hours ago
Flights from Denver (DEN) to Ontario (ONT)
Origin airport
Denver Intl.
Destination airport
Los Angeles - Ontario Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Hawaiian Airlines, JetBlue Airways, Southwest Airlines, United
Roundtrip price
$102
Distance
816 mi

Denver to Ontario Flights

The cheapest times to fly from Denver to Ontario

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Denver to Ontario are during the month of May. You can find some of the cheapest flights from Denver to Ontario with Expedia's search tool and vast selection of airlines.

The best time to book a flight from Denver to Ontario

Sunday is one of the best days to book for cheap flights from Denver to Ontario: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

How to find cheap round-trip tickets from Denver to Ontario

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Denver to Ontario in 2025. You can also book with separate airlines for your outbound and return journeys, from $54 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Denver to Ontario flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

You could also save big by booking one of Expedia's vacation packages. Bundling together your Denver to Ontario airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

*Terms apply.

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

Frequently asked questions

How long does it take to fly from Denver Airport to Ontario Airport?
A direct flight with Frontier Airlines takes roughly 2 hours and 24 minutes. Hop on the 10:31PM flight from Denver Airport and arrive at Los Angeles - Ontario Intl. Airport (ONT) at 11:55PM. Clinch a fantastic deal on this and many other routes when you use Expedia to book your trip.
Is it cheaper to buy a plane ticket from DIA airport to ONT last minute?
Booking your journey from Denver Airport to Los Angeles - Ontario Intl. Airport (ONT) at the last minute could save you money if you strike it lucky and find an epic deal. However, airfares generally don’t get cheaper closer to the departure date. If you wait around, flights could also be booked solid or the best seats gone (that could mean the middle seat!). If you’d prefer to play it safe, book well in advance of when you want to leave. In fact, Expedia has some of the biggest deals up to 12 months in advance. If your preferred carrier hasn’t released its fares yet, check back regularly as offers are constantly updated on Expedia.
What airline has the least delays from DIA airport to Los Angeles - Ontario Intl. Airport (ONT)?
If you’d prefer not to be stuck at the departure gate — or worse, have your vacation ruined due to a flight delay — pick United Airlines. Around 75% of its DEN to Ontario Airport services land on time. You can check your flight status before leaving for the airport through the Expedia App. It also delivers real-time notifications about gate changes and how to reach your hotel. You’ll have all the details in your pocket with our handy travel companion.
What airports do you fly into for Ontario from Denver?
Los Angeles - Ontario Intl. Airport (ONT), John Wayne Airport (SNA) and Long Beach Municipal Airport (LGB) are your choices when jetting from Denver to Ontario. About 3 mi east of the center of Ontario, Los Angeles - Ontario Intl. Airport (ONT) is the city’s main gateway. Consider factors like flight departure and arrival times and the distance to your hotel before you select an airport. Ontario Mills Shopping Mall and Toyota Arena are two top attractions to put on your must-see list when you arrive at your destination.
What are the most popular departure times for flights from DEN to Ontario Airport?
The most popular departure times for trips from DIA airport to Los Angeles - Ontario Intl. Airport (ONT) fall between 11:00 AM - 12:00 PM on United Airlines. Our suggestion is to take off in the morning. The earlier you do, the greater your chances of a delay-free flight with lighter air traffic in the sky.
Can I change the date of my flight from DEN to Ontario Airport?
Plans can get upended, so Expedia is here to help make things easy. To start, access your DEN to Ontario Airport itinerary through the Expedia Trips portal and read the fare rules and restrictions about change fees or other charges. If you booked your ticket in the last 24 hours, some airlines will allow you to cancel for free and book new flights. If you booked your fare more than 24 hours ago, contact us via our Customer Service portal to find out your options.

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*Available to One Key members.