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

Return flights

03 Sep - 04 Sep	Air Canada
30 Sep - 05 Oct	Air Canada
07 Sep - 09 Oct	TAP
08 Sep - 09 Oct	TAP
24 Sep - 01 Oct	TAP
09 Sep - 16 Sep	TAP
25 Sep - 02 Oct	TAP
11 Sep - 20 Sep	TAP
11 Sep - 19 Sep	TAP
08 Sep - 15 Sep	Icelandair
01 Sep - 08 Sep	Icelandair
02 Sep - 08 Sep	TAP
08 Sep - 17 Sep	Icelandair
01 Sep - 15 Sep	Icelandair
11 Sep - 15 Sep	TAP
22 Sep - 11 Oct	TAP
24 Sep - 05 Oct	TAP
27 Sep - 04 Oct	TAP
26 Sep - 04 Oct	TAP
23 Sep - 04 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.

Book a cheap hotel in London

Cheap car rent in London

Cheapest return flights from Boston to London in September from $372

Return flights