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

Return flights

14 Sep - 16 Sep	Air Canada
14 Sep - 15 Sep	Air Canada
07 Sep - 09 Sep	Iberia
07 Sep - 10 Sep	SWISS
28 Sep - 11 Oct	TAP
19 Sep - 21 Sep	Iberia
08 Sep - 11 Sep	Austrian Airlines
16 Sep - 21 Sep	Air Canada
13 Sep - 20 Sep	Aer Lingus
29 Sep - 25 Oct	Aer Lingus
30 Sep - 20 Oct	Aer Lingus
14 Sep - 04 Oct	Aer Lingus
22 Sep - 18 Oct	Aer Lingus
30 Sep - 25 Oct	Aer Lingus
29 Sep - 03 Oct	Aer Lingus
04 Sep - 11 Sep	Aer Lingus
29 Sep - 05 Oct	Aer Lingus
03 Sep - 04 Oct	Aer Lingus
26 Sep - 05 Oct	Aer Lingus
11 Sep - 15 Sep	Aer Lingus

Also check the deals for one-way flights from Boston to London 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 Boston to London in September from $373

Return flights