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

Return flights

06 Dec - 12 Dec	SWISS
02 Dec - 09 Dec	easyJet
10 Dec - 14 Jan	easyJet
03 Dec - 08 Dec	easyJet
09 Dec - 16 Dec	easyJet
09 Dec - 17 Dec	easyJet
06 Dec - 13 Dec	Transavia France
06 Dec - 10 Dec	easyJet
09 Dec - 18 Dec	easyJet
11 Dec - 15 Dec	KLM
09 Dec - 19 Dec	easyJet
30 Dec - 01 Jan	easyJet
18 Dec - 07 Jan	easyJet
29 Dec - 07 Jan	easyJet
29 Dec - 01 Jan	easyJet
21 Dec - 04 Jan	TUI
18 Dec - 02 Jan	easyJet
20 Dec - 04 Jan	easyJet
21 Dec - 02 Jan	easyJet
24 Dec - 01 Jan	easyJet

Also check the deals for one-way flights from Keflavik to Madrid 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 Madrid in December from 158€

Return flights