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

Return flights

12 Oct - 20 Oct	Icelandair
06 Oct - 10 Oct	Icelandair
06 Oct - 14 Oct	Icelandair
31 Oct - 12 Nov	Icelandair
13 Oct - 18 Oct	Icelandair
04 Oct - 11 Oct	Icelandair
25 Oct - 28 Oct	Alaska Airlines
06 Oct - 21 Oct	jetBlue
07 Oct - 21 Oct	jetBlue

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 $623

Return flights