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

Return flights

05 May - 13 May	Icelandair
04 May - 11 May	Finnair
05 May - 12 May	Delta
06 May - 13 May	Finnair
07 May - 14 May	Air Canada
07 May - 20 May	Air Canada
11 May - 18 May	Finnair
12 May - 19 May	KLM
12 May - 24 May	Turkish Airlines
01 May - 08 May	Finnair
26 May - 02 Jun	Turkish Airlines
25 May - 01 Jun	Brussels Airlines
28 May - 04 Jun	Icelandair
27 May - 03 Jun	Icelandair
29 May - 05 Jun	jetBlue
30 May - 06 Jun	Aer Lingus

Also check the deals for one-way flights from Denver 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 Denver to Lisbon in May from $576

Return flights