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

Return flights

09 Dec - 16 Dec	Iberia For Level
29 Dec - 12 Jan	Iberia For Level
12 Dec - 14 Dec	Austrian Airlines
04 Dec - 09 Dec	TAP
11 Dec - 15 Dec	Aer Lingus
23 Dec - 20 Jan	Icelandair
14 Dec - 21 Dec	Air Canada
16 Dec - 23 Dec	Air Canada
25 Dec - 08 Jan	Air Canada
06 Dec - 20 Dec	Aer Lingus
22 Dec - 29 Dec	Iberia For Level
15 Dec - 21 Dec	Air Canada
22 Dec - 30 Dec	Air Canada
29 Dec - 12 Jan	American Airlines	direct
25 Dec - 01 Jan	Air Canada
24 Dec - 04 Jan	Air Canada
23 Dec - 05 Jan	Air Canada
26 Dec - 05 Jan	Air Canada
26 Dec - 01 Jan	Air Canada
24 Dec - 02 Jan	Icelandair

Also check the deals for one-way flights from Boston 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 Boston to London in December from $420

Return flights