Cheapest one-way flights from Seattle to London in September from $246

Best time to book flights for Seattle (SEA) to London (LHR) flights at AirHint

AirHint found the following cheapest one-way flights from Seattle (SEA) to London (LHR) in September 2025 (see full year).

One-Way flights

21 Sep Icelandair
28 Sep Icelandair
14 Sep Icelandair
15 Sep Icelandair
04 Sep Icelandair
06 Sep Icelandair
29 Sep Air France direct
07 Sep Air France direct
28 Sep American Airlines direct
21 Sep Air France direct

Also check the deals for return flights from Seattle to London in September.

Skyscanner

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

Book a cheap hotel in London

Cheap car rent in London