$414 Cheap American Airlines flights Seattle (SEA) to London (LHR)

Use the "Price (lowest to highest)" filter on Expedia to find cheap American Airlines return flights from $520 from SEA to LHR. Affordable one-way options from $414 are also on offer.**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.

Landing the best American Airlines deals from SEA to LHR often comes down to booking at the right moment. You can save 17% on international flights when you book 18 to 29 days before takeoff instead of four to five months ahead. Better still, you can pocket 17% on average by buying your fare on a Sunday rather than a Friday, which is often the most expensive day to book.* It's a good idea to start searching for flights about one month before your travel dates.*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.

Sort your results by "Morning" and "Early Morning" to browse the earliest departures from SEA to LHR. Heading 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.