AirHint found the following cheapest return flights from Washington (IAD) to London (STN) in December 2025 (see full year).

Return flights

30 Dec - 12 Jan	Icelandair
06 Dec - 10 Dec	SWISS
09 Dec - 16 Dec	Icelandair
15 Dec - 12 Jan	Icelandair
06 Dec - 08 Dec	SWISS
27 Dec - 10 Jan	Aer Lingus
27 Dec - 11 Jan	Aer Lingus
07 Dec - 14 Dec	Lufthansa
12 Dec - 14 Dec	Aer Lingus
31 Dec - 07 Jan	Air Canada
29 Dec - 14 Jan	Icelandair
30 Dec - 14 Jan	Iberia
07 Dec - 24 Dec	Air Canada
08 Dec - 24 Dec	Icelandair
08 Dec - 23 Dec	Icelandair
09 Dec - 14 Dec	Icelandair
11 Dec - 15 Dec	Aer Lingus
29 Dec - 12 Jan	SWISS
28 Dec - 12 Jan	Lufthansa
12 Dec - 11 Jan	Aer Lingus

Also check the deals for one-way flights from Washington to London in December.

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 Washington to London in December from $601

Return flights