Cheapest return flights from Seattle to London in September from 415€

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

Return flights

21 Sep - 28 Sep Icelandair
05 Sep - 14 Sep Icelandair
11 Sep - 20 Sep Icelandair
13 Sep - 20 Sep Icelandair
03 Sep - 10 Sep KLM
04 Sep - 11 Sep Icelandair
10 Sep - 17 Sep Icelandair
16 Sep - 23 Sep Icelandair
19 Sep - 26 Sep Icelandair
13 Sep - 22 Sep Icelandair
26 Sep - 03 Oct Icelandair
25 Sep - 08 Oct Icelandair
29 Sep - 18 Oct Icelandair
26 Sep - 05 Oct Icelandair
28 Sep - 05 Oct British Airways direct
26 Sep - 03 Oct Air France direct
29 Sep - 18 Oct Virgin Atlantic direct
25 Sep - 02 Oct Icelandair
26 Sep - 05 Oct Air France direct
25 Sep - 02 Oct British Airways direct

Also check the deals for one-way 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.

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