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

Return flights

25 Sep - 09 Oct	Wizz Air Malta
10 Sep - 13 Sep	Fly Play
11 Sep - 14 Sep	KLM
10 Sep - 17 Sep	Fly Play
11 Sep - 18 Sep	Wizz Air Malta
25 Sep - 07 Oct	Wizz Air Malta
29 Sep - 06 Oct	Fly Play
07 Sep - 14 Sep	Wizz Air
22 Sep - 06 Oct	Fly Play
26 Sep - 08 Oct	easyJet
06 Sep - 13 Sep	Wizz Air
17 Sep - 19 Sep	Fly Play
26 Sep - 10 Oct	easyJet
26 Sep - 05 Oct	easyJet
26 Sep - 03 Oct	Fly Play
12 Sep - 19 Sep	Fly Play
10 Sep - 13 Sep	Iberia	direct
17 Sep - 19 Sep	Fly Play	direct
26 Sep - 05 Oct	Fly Play	direct
26 Sep - 08 Oct	Fly Play	direct

Also check the deals for one-way flights from Keflavik to Madrid 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 Keflavik to Madrid in September from 170€

Return flights