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

Return flights

01 Sep - 08 Sep	Icelandair
08 Sep - 17 Sep	TAP
22 Sep - 11 Oct	TAP
10 Sep - 24 Sep	TAP
10 Sep - 20 Sep	TAP
20 Sep - 28 Sep	TAP
20 Sep - 27 Sep	TAP
22 Sep - 28 Sep	TAP
27 Sep - 04 Oct	TAP
17 Sep - 30 Sep	TAP
15 Sep - 21 Sep	TAP
24 Sep - 28 Sep	TAP
24 Sep - 01 Oct	TAP
24 Sep - 05 Oct	TAP
26 Sep - 04 Oct	TAP
23 Sep - 04 Oct	TAP
26 Sep - 05 Oct	TAP
25 Sep - 02 Oct	Spirit Airlines
09 Sep - 09 Oct	TAP
30 Sep - 05 Oct	TAP

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 $366

Return flights