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

Return flights

03 Dec - 12 Dec	British Airways
04 Dec - 11 Dec	Finnair
02 Dec - 23 Dec	British Airways
03 Dec - 24 Dec	British Airways
01 Dec - 08 Dec	United
11 Dec - 18 Dec	United
23 Dec - 30 Dec	Air Canada
25 Dec - 18 Jan	Air Canada
20 Dec - 07 Jan	Air Canada
20 Dec - 30 Dec	Air Canada
20 Dec - 06 Jan	Air Canada
23 Dec - 02 Jan	Air Canada
21 Dec - 27 Dec	Air Canada
22 Dec - 03 Jan	Air Canada
22 Dec - 04 Jan	Air Canada
30 Dec - 02 Jan	Air Canada
30 Dec - 03 Jan	Air Canada
19 Dec - 06 Jan	Air Canada
21 Dec - 04 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.

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Cheapest return flights from Washington to London in December from $573

Return flights