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

Return flights

08 Jan - 16 Jan	Icelandair
08 Jan - 20 Jan	Icelandair
24 Jan - 31 Jan	Icelandair
11 Jan - 29 Jan	Icelandair
18 Jan - 31 Jan	Icelandair
08 Jan - 31 Jan	Icelandair
19 Jan - 26 Jan	Icelandair
08 Jan - 15 Jan	Icelandair
11 Jan - 18 Jan	Icelandair
14 Jan - 21 Jan	Icelandair
29 Jan - 05 Feb	Icelandair
14 Jan - 07 Feb	Icelandair
13 Jan - 07 Feb	Icelandair
26 Jan - 09 Feb	Delta
29 Jan - 05 Feb	British Airways	direct
14 Jan - 07 Feb	Finnair	direct
13 Jan - 07 Feb	British Airways	direct
27 Jan - 21 Feb	Air France	direct

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 412€

Return flights