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

Return flights

01 Dec - 10 Dec	TAP
01 Dec - 07 Dec	TAP
02 Dec - 10 Dec	Icelandair
05 Dec - 10 Dec	TAP
04 Dec - 12 Dec	Icelandair
01 Dec - 13 Dec	Aer Lingus
04 Dec - 11 Dec	Icelandair
01 Dec - 08 Dec	Lufthansa
29 Dec - 24 Jan	Icelandair
30 Dec - 24 Jan	Icelandair
31 Dec - 24 Jan	Icelandair
08 Dec - 07 Jan	Icelandair
15 Dec - 10 Jan	Icelandair
16 Dec - 16 Jan	Icelandair
15 Dec - 08 Jan	Icelandair
16 Dec - 10 Jan	Icelandair
30 Dec - 09 Jan	SWISS
08 Dec - 13 Dec	TAP
29 Dec - 14 Jan	Icelandair
01 Dec - 14 Dec	TAP

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.

Book a cheap hotel in London

Cheap car rent in London

Cheapest return flights from Washington to London in December from 381€

Return flights