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

Return flights

01 Dec - 08 Dec	Air Canada
03 Dec - 12 Dec	Air Canada
29 Dec - 07 Jan	Scandinavian Airlines
03 Dec - 12 Dec	British Airways	direct
04 Dec - 11 Dec	British Airways	direct
01 Dec - 08 Dec	British Airways	direct
29 Dec - 06 Jan	Scandinavian Airlines
03 Dec - 01 Jan	Lufthansa
07 Dec - 01 Jan	SWISS
11 Dec - 28 Dec	Icelandair
28 Dec - 08 Jan	TAP
28 Dec - 07 Jan	TAP
24 Dec - 07 Jan	Icelandair
14 Dec - 21 Dec	British Airways	direct
25 Dec - 30 Dec	Icelandair
23 Dec - 31 Dec	Air Canada
29 Dec - 07 Jan	Delta	direct
24 Dec - 31 Dec	Lufthansa
28 Dec - 06 Jan	Lufthansa
22 Dec - 10 Jan	Air Canada

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 $477

Return flights