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

Return flights

14 Oct - 23 Oct	Icelandair
30 Oct - 06 Nov	United
31 Oct - 07 Nov	KLM
04 Oct - 11 Oct	Aer Lingus
04 Oct - 16 Oct	Aer Lingus
10 Oct - 17 Oct	Aer Lingus
16 Oct - 01 Nov	Delta
17 Oct - 01 Nov	Delta
13 Oct - 17 Oct	Air Canada

Also check the deals for one-way flights from Denver 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 Denver to Lisbon in October from 478€

Return flights