$143 Cheap United flights Las Vegas (LAS) to Ontario (ONT)

Finding cheap one-way United Airlines flights from LAS to ONT from $143 on Expedia is a cinch --- just filter by "Price (lowest to highest)." Or check out our budget-friendly return fares from $285 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.

For cheap United Airlines fares from Harry Reid Intl. Airport (LAS) to Los Angeles - Ontario Intl. Airport (ONT), start searching one to three months before your planned departure. Securing 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 price you pay. Sunday is usually the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by choosing to book 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 find the earliest departures from LAS to ONT with United Airlines, filter your results by "Morning" and "Early Morning." Booking an early flight generally means you'll experience fewer cancellations.**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.

Offering a rewarding loyalty program, United Airlines is a top pick for many passengers departing from LAS to ONT. Plus, as a United Mileage Plus and One Key™ member booking through Expedia, you could earn OneKeyCash™* on eligible flights along with your airline miles.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.