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

Return flights

04 Dec - 09 Dec	easyJet
11 Dec - 14 Dec	easyJet
08 Dec - 11 Dec	easyJet
07 Dec - 11 Dec	Icelandair	direct
16 Dec - 23 Dec	easyJet
13 Dec - 05 Jan	easyJet
14 Dec - 07 Jan	easyJet
14 Dec - 08 Jan	easyJet
07 Dec - 14 Dec	easyJet
14 Dec - 21 Dec	easyJet
18 Dec - 01 Jan	easyJet
11 Dec - 14 Dec	Icelandair	direct
07 Dec - 14 Dec	Icelandair	direct
31 Dec - 04 Jan	easyJet
14 Dec - 21 Dec	Icelandair	direct
21 Dec - 01 Jan	TUI
28 Dec - 01 Jan	easyJet
28 Dec - 01 Jan	Icelandair	direct
14 Dec - 08 Jan	Icelandair	direct
21 Dec - 04 Jan	TUI

Also check the deals for one-way flights from Keflavik to Lisbon 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 Keflavik to Lisbon in December from 205€

Return flights