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

Return flights

14 Jan - 22 Jan	Icelandair
27 Jan - 02 Feb	Icelandair
22 Jan - 29 Jan	Icelandair
13 Jan - 17 Jan	Icelandair
13 Jan - 20 Jan	Icelandair
13 Jan - 31 Jan	Icelandair
22 Jan - 04 Feb	Icelandair
24 Jan - 28 Feb	Icelandair
20 Jan - 27 Jan	Icelandair
24 Jan - 31 Jan	Icelandair
09 Jan - 15 Jan	Icelandair
17 Jan - 01 Feb	Icelandair
31 Jan - 08 Feb	Icelandair
24 Jan - 28 Feb	British Airways	direct
22 Jan - 04 Feb	British Airways	direct
27 Jan - 02 Feb	British Airways	direct
22 Jan - 29 Jan	American Airlines	direct
14 Jan - 18 Jan	Icelandair

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

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 January from $503

Return flights