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

Return flights

08 Sep - 19 Sep	Austrian Airlines
10 Sep - 28 Sep	TAP
25 Sep - 04 Oct	TAP
10 Sep - 23 Sep	SWISS
11 Sep - 23 Sep	SWISS
24 Sep - 05 Oct	Scandinavian Airlines
24 Sep - 06 Oct	SWISS
06 Sep - 13 Sep	SWISS
02 Sep - 09 Sep	SWISS
09 Sep - 23 Sep	TAP
16 Sep - 23 Sep	SWISS
15 Sep - 22 Sep	SWISS
08 Sep - 16 Sep	SWISS
25 Sep - 09 Oct	TAP
18 Sep - 05 Oct	Scandinavian Airlines
25 Sep - 05 Oct	SWISS
25 Sep - 02 Oct	TAP
25 Sep - 06 Oct	TAP
25 Sep - 03 Oct	Scandinavian Airlines
24 Sep - 03 Oct	Scandinavian Airlines

Also check the deals for one-way flights from London to Boston in September.

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 September from 337€

Return flights