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

Return flights

26 Dec - 09 Jan	British Airways
31 Dec - 07 Jan	Icelandair
24 Dec - 31 Dec	SWISS
26 Dec - 30 Dec	LOT
26 Dec - 31 Dec	British Airways
30 Dec - 04 Jan	Frontier Airlines
28 Dec - 04 Jan	TAP
28 Dec - 02 Jan	TAP
26 Dec - 03 Jan	United
26 Dec - 31 Dec	TAP	direct
26 Dec - 09 Jan	TAP	direct
28 Dec - 04 Jan	TAP	direct
24 Dec - 31 Dec	TAP	direct
28 Dec - 02 Jan	TAP	direct
26 Dec - 02 Jan	TAP	direct

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 669€

Return flights