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

Return flights

29 Sep - 02 Oct	Ryanair
30 Sep - 09 Oct	Wizz Air
22 Sep - 02 Oct	Ryanair
25 Sep - 04 Oct	Ryanair
20 Sep - 02 Oct	Wizz Air
24 Sep - 27 Sep	easyJet
28 Sep - 08 Oct	Fly Play	direct
17 Sep - 02 Oct	Wizz Air
26 Sep - 08 Oct	Ryanair
20 Sep - 27 Sep	Wizz Air
28 Sep - 02 Oct	Fly Play	direct
29 Sep - 06 Oct	Ryanair
20 Sep - 25 Sep	Wizz Air
23 Sep - 25 Sep	Transavia France
24 Sep - 28 Sep	easyJet
19 Sep - 27 Sep	Wizz Air
16 Sep - 27 Sep	Air Europa
23 Sep - 27 Sep	Wizz Air
16 Sep - 25 Sep	Air Europa
24 Sep - 29 Sep	easyJet

Also check the deals for one-way flights from Madrid to Keflavik in September.

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 Madrid to Keflavik in September from 235€

Return flights