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

Return flights

18 Aug - 28 Aug	TAP	direct
15 Aug - 29 Aug	TAP	direct
18 Aug - 29 Aug	TAP	direct
21 Aug - 28 Aug	TAP	direct
16 Aug - 23 Aug	TAP	direct
04 Aug - 29 Aug	TAP	direct
24 Aug - 04 Sep	TAP	direct
23 Aug - 31 Aug	Icelandair
14 Aug - 23 Aug	TAP	direct
22 Aug - 29 Aug	TAP	direct
22 Aug - 04 Sep	TAP	direct
13 Aug - 24 Aug	Icelandair
19 Aug - 17 Sep	United
26 Aug - 04 Sep	Turkish Airlines
26 Aug - 02 Sep	Aer Lingus
02 Aug - 07 Sep	TAP	direct
28 Aug - 06 Sep	Aer Lingus
29 Aug - 07 Sep	Aer Lingus
30 Aug - 06 Sep	TAP	direct
29 Aug - 06 Sep	Aer Lingus

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 $469

Return flights