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

Return flights

08 Dec - 16 Dec	Air Canada
24 Dec - 17 Jan	Spirit Airlines
02 Dec - 27 Dec	TAP
07 Dec - 27 Dec	Frontier Airlines
23 Dec - 08 Jan	Frontier Airlines
26 Dec - 09 Jan	Frontier Airlines
07 Dec - 27 Dec	Iberia	direct
02 Dec - 27 Dec	Iberia	direct
21 Dec - 08 Jan	Frontier Airlines
22 Dec - 08 Jan	Spirit Airlines
20 Dec - 10 Jan	Frontier Airlines
20 Dec - 08 Jan	Frontier Airlines
19 Dec - 08 Jan	Frontier Airlines
22 Dec - 08 Jan	Finnair	direct
23 Dec - 08 Jan	Iberia	direct

Also check the deals for one-way flights from Philadelphia to Lisbon 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 Lisbon in December from 529€

Return flights