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

Return flights

13 Sep - 29 Sep	Air Canada
14 Sep - 01 Oct	Air Canada
14 Sep - 26 Sep	Air Canada
01 Sep - 12 Sep	Air Canada
01 Sep - 30 Sep	Air Canada
01 Sep - 15 Sep	Air Canada
03 Sep - 10 Sep	Air Canada
19 Sep - 21 Sep	Air Canada
17 Sep - 24 Sep	Air Canada
09 Sep - 16 Sep	Air Canada
21 Sep - 30 Sep	Air Canada
22 Sep - 07 Oct	Air Canada
21 Sep - 02 Oct	Air Canada
14 Sep - 01 Oct	Delta	direct
21 Sep - 02 Oct	American Airlines	direct
15 Sep - 06 Oct	TAP
05 Sep - 07 Oct	Delta
22 Sep - 06 Oct	Delta	direct
15 Sep - 06 Oct	British Airways	direct
22 Sep - 07 Oct	British Airways	direct

Also check the deals for one-way flights from San Francisco 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 San Francisco to London in September from $466

Return flights