$99 Cheap United flights Ontario (ONT) to Portland (PDX)

Landing cheap one-way United Airlines flights from ONT to PDX from $99 on Expedia couldn't be simpler — just filter by "Price (lowest to highest)." Or check out our budget-friendly round-trip fares from $159 for your next exciting vacation.**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.

To find cheap United Airlines fares from Los Angeles - Ontario Intl. Airport (ONT) to Portland Intl. Airport (PDX), start searching one to three months before your intended 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 how much you pay. Sunday is typically the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking 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.

Filter your results by "Early Morning" and "Morning" to find the earliest departures from ONT to PDX. Jetting off early means flight 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.

Depart from ONT to PDX with United Airlines and you can look forward to a range of benefits starting with a rewarding loyalty program. When you book through Expedia as a United Mileage Plus and One Key™ member, you can also earn OneKeyCash™* to redeem on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.