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

Return flights

24 Oct - 31 Oct	TAP	direct
28 Oct - 04 Nov	United
17 Oct - 24 Oct	TAP	direct
13 Oct - 08 Nov	SWISS
14 Oct - 08 Nov	Aer Lingus
20 Oct - 28 Oct	SWISS
29 Oct - 05 Nov	TAP	direct
07 Oct - 21 Oct	Lufthansa
08 Oct - 15 Oct	Lufthansa
10 Oct - 17 Oct	TAP	direct
02 Oct - 16 Oct	Turkish Airlines
11 Oct - 22 Oct	Turkish Airlines
19 Oct - 23 Oct	Finnair
17 Oct - 25 Oct	British Airways
09 Oct - 01 Nov	SWISS
30 Oct - 02 Nov	Delta

Also check the deals for one-way flights from Chicago to Lisbon in October.

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 October from 417€

Return flights