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

Return flights

11 Dec - 17 Dec	ITA Airways
04 Dec - 08 Dec	SWISS
11 Dec - 31 Dec	Delta
12 Dec - 31 Dec	Delta
15 Dec - 12 Jan	Delta
11 Dec - 23 Jan	Iberia
03 Dec - 07 Dec	KLM
24 Dec - 24 Jan	SWISS
15 Dec - 15 Jan	SWISS
23 Dec - 10 Jan	SWISS
17 Dec - 29 Dec	SWISS
14 Dec - 11 Jan	SWISS
22 Dec - 13 Jan	SWISS
23 Dec - 07 Jan	ITA Airways
26 Dec - 12 Jan	Delta
24 Dec - 31 Dec	Delta
24 Dec - 29 Dec	SWISS
10 Dec - 14 Dec	British Airways
15 Dec - 28 Dec	British Airways
18 Dec - 13 Jan	SWISS

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 $599

Return flights