Cheap flights from Denver to ONT
Recently found return fares from $71, with November the cheapest month we know of. Compare dates, then book with the partner you choose.
Cheapest months to fly
Lowest recently found return fare in each month. Tap a month to see that month's calendar.
Denver → ONT
November 2026
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LowerHigherLowest this month
Lowest fares for the best day
- Frontier AirlinesSat 7 Nov – Mon 9 Nov · Direct · 2h 22m $137
Airport in Denver
- DENDenver International
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FAQ
Questions about this route
Still have a question?
Search the help center or send us a message. We reply by email.
Help center Contact us01What is the cheapest month to fly from Denver to ONT?
Based on recently found fares, November 2026 has the lowest price we know of, from $71. Prices change often, so check the calendar for current fares.
02Are the prices on this page final?
No. They are recently found fares. When you open a deal, the partner shows the live price, including taxes and fees, before you pay.
03How can I get an alert when flights to ONT get cheaper?
Use the price alert on this page. Choose your dates or a whole month and we will email you when the fare drops.