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

Return flights

04 Dec - 08 Dec	Spirit Airlines
04 Dec - 06 Dec	Spirit Airlines
07 Dec - 16 Dec	Air Canada
16 Dec - 29 Dec	Aer Lingus
10 Dec - 17 Dec	Air Canada
10 Dec - 23 Dec	Air Canada
03 Dec - 14 Dec	SWISS
06 Dec - 13 Dec	Spirit Airlines
12 Dec - 07 Jan	Spirit Airlines
16 Dec - 23 Dec	Air Canada
12 Dec - 04 Jan	Spirit Airlines
18 Dec - 16 Jan	TAP
16 Dec - 16 Jan	TAP
30 Dec - 04 Jan	Air Canada
29 Dec - 04 Jan	Air Canada
17 Dec - 28 Dec	TAP
30 Dec - 02 Jan	Aer Lingus
18 Dec - 02 Jan	Spirit Airlines

Also check the deals for one-way flights from Philadelphia to London in December.

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 December from $546

Return flights