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

Return flights

03 Dec - 10 Dec	TAP
11 Dec - 17 Dec	TAP
03 Dec - 08 Dec	TAP
04 Dec - 07 Dec	TAP
01 Dec - 12 Dec	TAP
03 Dec - 11 Dec	TAP
05 Dec - 11 Dec	TAP
09 Dec - 14 Dec	TAP
06 Dec - 14 Dec	TAP
04 Dec - 08 Dec	TAP
13 Dec - 12 Jan	Icelandair
13 Dec - 14 Jan	Icelandair
29 Dec - 24 Jan	Icelandair
16 Dec - 13 Jan	Icelandair
25 Dec - 17 Jan	Icelandair
15 Dec - 17 Jan	Icelandair
15 Dec - 10 Jan	Icelandair
15 Dec - 09 Jan	Icelandair
05 Dec - 12 Jan	Frontier Airlines
23 Dec - 17 Jan	Icelandair

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 $423

Return flights