AirHint found the following cheapest return flights from Chicago (ORD) to Lisbon (LIS) in May 2026 (see full year).

Return flights

06 May - 10 May	Icelandair
05 May - 12 May	Icelandair
03 May - 12 May	Icelandair
04 May - 12 May	Delta
01 May - 06 May	Icelandair
01 May - 08 May	Finnair
06 May - 13 May	British Airways
01 May - 09 May	British Airways
02 May - 13 May	Aer Lingus
06 May - 17 May	British Airways
31 May - 26 Jun	Air Canada
26 May - 02 Jun	Finnair
25 May - 01 Jun	SWISS
31 May - 26 Jun	TAP	direct

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

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 May from $436

Return flights