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

Return flights

08 Dec - 11 Dec	Ryanair
03 Dec - 06 Dec	Ryanair
04 Dec - 11 Dec	Ryanair
09 Dec - 13 Dec	easyJet
02 Dec - 09 Dec	easyJet
08 Dec - 15 Dec	easyJet
03 Dec - 09 Dec	Ryanair
04 Dec - 09 Dec	easyJet
04 Dec - 10 Dec	Ryanair
07 Dec - 10 Dec	Ryanair
21 Dec - 01 Jan	easyJet
21 Dec - 04 Jan	TAP
31 Dec - 04 Jan	Ryanair
21 Dec - 01 Jan	Icelandair	direct
30 Dec - 05 Jan	Wizz Air
31 Dec - 05 Jan	easyJet
29 Dec - 01 Jan	easyJet
29 Dec - 03 Jan	easyJet
26 Dec - 04 Jan	Scandinavian Airlines
28 Dec - 01 Jan	Ryanair

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 194€

Return flights