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

Return flights

15 Oct - 22 Oct	Icelandair
01 Oct - 07 Oct	Aer Lingus
29 Oct - 04 Nov	Air France
21 Oct - 26 Oct	Aer Lingus
02 Oct - 06 Oct	Icelandair
10 Oct - 18 Oct	Scandinavian Airlines
21 Oct - 28 Oct	Lufthansa
01 Oct - 06 Oct	Icelandair
09 Oct - 17 Oct	Icelandair
19 Oct - 26 Oct	Lufthansa
10 Oct - 01 Nov	Lufthansa
11 Oct - 19 Oct	Icelandair
15 Oct - 08 Nov	Scandinavian Airlines
22 Oct - 15 Nov	Icelandair
09 Oct - 07 Nov	WestJet
08 Oct - 01 Nov	Icelandair
19 Oct - 08 Nov	Icelandair
09 Oct - 08 Nov	WestJet
09 Oct - 09 Nov	WestJet
08 Oct - 07 Nov	Icelandair

Also check the deals for one-way flights from Seattle to London in October.

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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Cheapest return flights from Seattle to London in October from $551

Return flights