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

Return flights

12 Dec - 15 Dec	Fly Play	direct
01 Dec - 06 Dec	easyJet
08 Dec - 15 Dec	Fly Play	direct
08 Dec - 12 Dec	Fly Play	direct
01 Dec - 05 Dec	Fly Play	direct
01 Dec - 08 Dec	easyJet
01 Dec - 07 Dec	easyJet
05 Dec - 09 Dec	Ryanair
15 Dec - 19 Dec	Fly Play	direct
04 Dec - 08 Dec	Ryanair
31 Dec - 04 Jan	Ryanair
28 Dec - 04 Jan	Scandinavian Airlines
28 Dec - 04 Jan	Icelandair	direct
28 Dec - 05 Jan	transavia
27 Dec - 03 Jan	Ryanair
26 Dec - 03 Jan	easyJet

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 170€

Return flights