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

Return flights

08 Dec - 15 Dec	Fly Play	direct
12 Dec - 15 Dec	Fly Play	direct
05 Dec - 12 Dec	Fly Play	direct
03 Dec - 10 Dec	easyJet
10 Dec - 17 Dec	easyJet
01 Dec - 08 Dec	easyJet
22 Dec - 29 Dec	Fly Play	direct
04 Dec - 11 Dec	Vueling Airlines
19 Dec - 26 Dec	Fly Play	direct
19 Dec - 23 Dec	easyJet
28 Dec - 05 Jan	Scandinavian Airlines
26 Dec - 03 Jan	easyJet
29 Dec - 02 Jan	Fly Play	direct

Also check the deals for one-way flights from Lisbon to Keflavik in December.

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 Lisbon to Keflavik in December from $184

Return flights