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

Return flights

28 Jan - 05 Feb	Icelandair
30 Jan - 03 Feb	Icelandair
14 Jan - 20 Jan	Icelandair
31 Jan - 08 Feb	Icelandair
24 Jan - 29 Jan	Icelandair
20 Jan - 27 Jan	Icelandair
22 Jan - 29 Jan	Icelandair
24 Jan - 31 Jan	Icelandair
10 Jan - 17 Jan	Icelandair
29 Jan - 06 Feb	Icelandair
20 Jan - 02 Feb	Icelandair
28 Jan - 04 Feb	Icelandair
30 Jan - 06 Feb	Icelandair
22 Jan - 04 Feb	Icelandair
26 Jan - 02 Feb	Icelandair
22 Jan - 08 Feb	Lufthansa
23 Jan - 25 Jan	Lufthansa
07 Jan - 14 Jan	Icelandair
16 Jan - 23 Jan	WestJet
20 Jan - 25 Jan	Alaska Airlines

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 426€

Return flights