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

Return flights

05 Dec - 12 Dec	Fly Play	direct
08 Dec - 12 Dec	Fly Play	direct
08 Dec - 15 Dec	Fly Play	direct
01 Dec - 06 Dec	easyJet
01 Dec - 04 Dec	easyJet
01 Dec - 05 Dec	easyJet
08 Dec - 22 Dec	Fly Play	direct
06 Dec - 09 Dec	easyJet
02 Dec - 05 Dec	easyJet
01 Dec - 05 Dec	Fly Play	direct
18 Dec - 12 Jan	Vueling Airlines
26 Dec - 05 Jan	Fly Play	direct
26 Dec - 02 Jan	Fly Play	direct
31 Dec - 04 Jan	Ryanair
26 Dec - 01 Jan	easyJet
30 Dec - 04 Jan	TAP
27 Dec - 01 Jan	easyJet
28 Dec - 01 Jan	TAP
26 Dec - 04 Jan	Fly Play
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 155€

Return flights