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

Return flights

05 Dec - 10 Dec	TAP
06 Dec - 11 Dec	TAP
04 Dec - 08 Dec	TAP
08 Dec - 13 Dec	TAP
01 Dec - 15 Dec	SWISS
06 Dec - 14 Dec	SWISS
04 Dec - 14 Dec	SWISS
06 Dec - 13 Dec	Air Canada
05 Dec - 11 Dec	SWISS
03 Dec - 06 Dec	SWISS
30 Dec - 06 Jan	Austrian Airlines
17 Dec - 05 Jan	Air Canada
29 Dec - 05 Jan	Air Canada
17 Dec - 14 Jan	Air Canada
27 Dec - 06 Jan	Air Canada
27 Dec - 05 Jan	Air Canada
15 Dec - 08 Jan	Aer Lingus
15 Dec - 05 Jan	Air Canada
24 Dec - 05 Jan	Air Canada
22 Dec - 05 Jan	Icelandair

Also check the deals for one-way flights from London to Boston 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 London to Boston in December from $456

Return flights