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

Return flights

20 Aug - 24 Aug	Icelandair
17 Aug - 28 Aug	United
20 Aug - 27 Aug	United
19 Aug - 17 Sep	United
20 Aug - 26 Aug	SWISS
18 Aug - 28 Aug	TAP	direct
17 Aug - 28 Aug	TAP	direct
30 Aug - 07 Sep	Icelandair
23 Aug - 29 Aug	TAP	direct
15 Aug - 29 Aug	United
16 Aug - 27 Aug	United
08 Aug - 02 Sep	SWISS
07 Aug - 21 Aug	SWISS
07 Aug - 02 Sep	SWISS
29 Aug - 02 Sep	Aer Lingus
23 Aug - 06 Sep	Air Canada
26 Aug - 02 Sep	United
23 Aug - 06 Sep	TAP	direct
27 Aug - 05 Sep	SWISS
28 Aug - 01 Sep	Icelandair

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

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.

Book a cheap hotel in Lisbon

Cheap car rent in Lisbon

Cheapest return flights from Chicago to Lisbon in August from 412€

Return flights