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

Return flights

10 Sep - 15 Sep	Air Canada
10 Sep - 16 Sep	Air Canada
09 Sep - 17 Sep	Air Canada
24 Sep - 29 Sep	British Airways
24 Sep - 01 Oct	Spirit Airlines
28 Sep - 03 Oct	Spirit Airlines
25 Sep - 29 Sep	American Airlines
10 Sep - 24 Sep	jetBlue
14 Sep - 23 Sep	Air France
30 Sep - 02 Oct	Spirit Airlines
11 Sep - 12 Sep	Spirit Airlines
14 Sep - 17 Sep	Spirit Airlines
28 Sep - 02 Oct	Spirit Airlines
10 Sep - 04 Oct	jetBlue
30 Sep - 09 Oct	Spirit Airlines
06 Sep - 27 Sep	jetBlue
26 Sep - 11 Oct	jetBlue
16 Sep - 11 Oct	jetBlue
18 Sep - 11 Oct	jetBlue
17 Sep - 11 Oct	jetBlue

Also check the deals for one-way flights from Philadelphia 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 Philadelphia to London in September from $526

Return flights