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

Return flights

02 Sep - 23 Sep	Aer Lingus
02 Sep - 10 Sep	Aer Lingus
16 Sep - 23 Sep	Aer Lingus
02 Sep - 09 Sep	Aer Lingus
10 Sep - 30 Sep	Aer Lingus
17 Sep - 23 Sep	Aer Lingus
17 Sep - 06 Oct	Aer Lingus
17 Sep - 22 Sep	Aer Lingus
09 Sep - 14 Oct	Aer Lingus
03 Sep - 16 Oct	Aer Lingus
03 Sep - 11 Sep	Aer Lingus
02 Sep - 11 Sep	Aer Lingus
18 Sep - 13 Oct	SWISS
18 Sep - 27 Sep	SWISS
25 Sep - 04 Oct	United
17 Sep - 17 Oct	SWISS
18 Sep - 12 Oct	United
25 Sep - 05 Oct	United
25 Sep - 06 Oct	SWISS
12 Sep - 12 Oct	SWISS

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 $441

Return flights