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

Return flights

14 Sep - 24 Sep	Spirit Airlines
30 Sep - 06 Oct	Spirit Airlines
23 Sep - 14 Oct	Spirit Airlines
23 Sep - 01 Oct	Spirit Airlines
30 Sep - 21 Oct	British Airways
14 Sep - 22 Sep	Spirit Airlines
23 Sep - 15 Oct	Air Canada
10 Sep - 01 Oct	jetBlue
02 Sep - 16 Sep	jetBlue
09 Sep - 23 Sep	jetBlue
03 Sep - 17 Sep	jetBlue
02 Sep - 23 Sep	jetBlue
03 Sep - 24 Sep	jetBlue
02 Sep - 17 Sep	jetBlue
10 Sep - 24 Sep	jetBlue
09 Sep - 30 Sep	jetBlue
17 Sep - 08 Oct	Air Canada
23 Sep - 04 Oct	British Airways
25 Sep - 02 Oct	Spirit Airlines
24 Sep - 15 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 $487

Return flights