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

Return flights

09 Dec - 16 Dec	Air Canada
01 Dec - 09 Dec	Air Canada
10 Dec - 16 Dec	Delta
10 Dec - 17 Dec	Delta
02 Dec - 12 Jan	Finnair
11 Dec - 17 Dec	Iberia
22 Dec - 07 Jan	Virgin Atlantic
07 Dec - 01 Jan	Air Canada
28 Dec - 11 Jan	Air Canada
23 Dec - 28 Dec	Air Canada
24 Dec - 28 Dec	Delta
25 Dec - 11 Jan	British Airways
25 Dec - 18 Jan	British Airways
17 Dec - 24 Dec	Air Canada
21 Dec - 30 Dec	Air Canada
23 Dec - 01 Jan	Air Canada
20 Dec - 18 Jan	Air Canada
29 Dec - 05 Jan	United
30 Dec - 05 Jan	Air Canada
17 Dec - 28 Dec	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 408€

Return flights