AirHint found the following cheapest return flights from Seattle (SEA) to London (STN) in April 2026 (see full year).

Return flights

20 Apr - 28 Apr	Icelandair
24 Apr - 28 Apr	Icelandair
22 Apr - 29 Apr	Icelandair
07 Apr - 14 Apr	Icelandair
23 Apr - 27 Apr	Icelandair
14 Apr - 20 Apr	Icelandair
25 Apr - 09 May	Icelandair
16 Apr - 30 Apr	Icelandair
23 Apr - 30 Apr	Icelandair
06 Apr - 15 Apr	Icelandair
24 Apr - 09 May	Icelandair
15 Apr - 22 Apr	Icelandair
29 Apr - 06 May	Icelandair
06 Apr - 07 May	Icelandair
29 Apr - 12 May	Icelandair
29 Apr - 13 May	Turkish Airlines

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

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 April from $465

Return flights