$109 Cheap Delta flights Denver (DEN) to Ontario (ONT)

Set the “Price (lowest to highest)” filter on Expedia to look for cheap Delta Air Lines round-trip flights from $211 from DEN to ONT. Affordable one-way tickets from $109 are available as well.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Search for return or one-way flights to Ontario in January or April. You could find cheaper fares with Delta Air Lines during these quieter months.

To find cheap Delta Air Lines fares from Denver Intl. Airport (DEN) to Los Angeles - Ontario Intl. Airport (ONT), start searching one to three months before your planned departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also impact the cost. Sunday tends to be the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your journey on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC’s global airline sales database.

To see if there’s a direct journey from DEN to ONT with Delta Air Lines or any other carriers, check the “Nonstop” filter when searching for tickets.

To find the earliest departures from DEN to ONT with Delta Air Lines, sort your results by “Morning” and “Early Morning.” Choosing an early flight usually means cancellations are less likely.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG’s global flight data platform.

Delta Air Lines flights from Denver Intl. Airport (DEN) to Ontario land at Los Angeles - Ontario Intl. Airport (ONT). This is the main gateway to this city.

With an excellent in-flight experience and a rewarding loyalty program, Delta Air Lines is a popular option for many travelers heading from DEN to ONT. Plus, if you’re a Delta SkyMiles and One Key™ member booking with Expedia, you could earn OneKeyCash™* on eligible flights on top of your airline miles, which can go toward future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.

Changes are typically free within 24 hours of making your booking, but your airline may add a charge after that. For more information about altering your flights, head to your “Trips,” select your flight and click on “Manage Booking.” If you want the freedom to update your itinerary without additional charges, apply the “Changes included” or “No cancel fee” filter when organizing your next trip.