$384 Cheap United flights Denver (DEN) to London (LHR)

Scoring cheap one-way United Airlines flights from DEN to LHR from $384 on Expedia is a breeze — just filter by "Price (lowest to highest)." Alternatively, check out our budget-friendly return fares from $517 for your next adventure.**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 United Airlines flights from DEN to LHR about one month before you want to leave. The cheapest time to reserve an international flight is usually 18 to 29 days ahead of your departure date when you can save 17% versus booking four to five months in advance. No matter your itinerary or ticket type, the best day of the week to book international airfare is usually Sunday. Friday is often the most expensive. Travelers booking on a Sunday can save 17% on average compared to those who book on a Friday.**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.

The first United Airlines flight from DEN to LHR departs at 5:35PM UTC-7, arriving at 9:40AM UTC+0. If you'd like to jet off later in the day, the last United Airlines flight leaves DEN at 5:35PM UTC-7 and lands at LHR at 9:40AM UTC+0. Flying before noon is often a good idea as morning flights are least likely to face 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.

A rewarding loyalty program and the ability to rack up points through United Mileage Plus are the start of the reasons to jet off from DEN to LHR with United Airlines. Plus, when you sign up to Expedia's free One Key™ program, you can earn OneKeyCash™* alongside any airline loyalty program earnings. It's yours to spend on your next adventure.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.