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

Return flights

18 Aug - 25 Aug	Fly Play	direct
04 Aug - 18 Aug	Fly Play	direct
31 Aug - 07 Sep	Fly Play
24 Aug - 31 Aug	Fly Play
11 Aug - 18 Aug	Fly Play	direct
15 Aug - 25 Aug	Wizz Air Malta
22 Aug - 29 Aug	Fly Play	direct
15 Aug - 25 Aug	Fly Play	direct
17 Aug - 25 Aug	Wizz Air Malta
15 Aug - 24 Aug	Wizz Air Malta
07 Aug - 12 Aug	Iberia Express
24 Aug - 14 Sep	Vueling Airlines
31 Aug - 14 Sep	Vueling Airlines
29 Aug - 05 Sep	Fly Play	direct
17 Aug - 07 Sep	Vueling Airlines
24 Aug - 07 Sep	Vueling Airlines

Also check the deals for one-way flights from Keflavik 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.

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Cheapest return flights from Keflavik to Lisbon in August from 236€

Return flights