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

Return flights

28 Dec - 11 Jan	Scandinavian Airlines
02 Dec - 09 Dec	United
09 Dec - 16 Dec	United
03 Dec - 10 Dec	United
08 Dec - 18 Dec	Aer Lingus
10 Dec - 19 Dec	Aer Lingus
07 Dec - 17 Dec	Air Canada
10 Dec - 17 Dec	Air Canada
06 Dec - 13 Dec	Scandinavian Airlines
08 Dec - 15 Dec	Lufthansa
04 Dec - 11 Dec	United
29 Dec - 24 Jan	Aer Lingus
31 Dec - 07 Jan	Air Canada
26 Dec - 11 Jan	Scandinavian Airlines
17 Dec - 09 Jan	KLM
31 Dec - 07 Jan	TAP	direct
28 Dec - 04 Jan	Scandinavian Airlines
28 Dec - 11 Jan	TAP	direct
17 Dec - 09 Jan	TAP	direct
26 Dec - 01 Jan	Aer Lingus

Also check the deals for one-way flights from Chicago 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 Chicago to Lisbon in December from $464

Return flights