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

Return flights

02 Dec - 09 Dec	SWISS
03 Dec - 07 Dec	SWISS
09 Dec - 16 Dec	SWISS
10 Dec - 16 Dec	SWISS
08 Dec - 11 Dec	SWISS
16 Dec - 10 Jan	SWISS
05 Dec - 08 Dec	Delta
08 Dec - 14 Dec	Delta
01 Dec - 05 Dec	Delta
05 Dec - 29 Dec	Delta
14 Dec - 14 Jan	KLM
04 Dec - 14 Dec	SWISS
30 Dec - 07 Jan	SWISS
15 Dec - 09 Jan	KLM
27 Dec - 06 Jan	SWISS
27 Dec - 07 Jan	SWISS
28 Dec - 06 Jan	SWISS
31 Dec - 05 Jan	Delta
23 Dec - 06 Jan	SWISS
22 Dec - 06 Jan	Delta

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 $538

Return flights