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

Return flights

30 Sep - 06 Oct	easyJet
30 Sep - 11 Oct	easyJet
23 Sep - 01 Oct	easyJet
26 Sep - 03 Oct	easyJet
26 Sep - 04 Oct	easyJet
24 Sep - 02 Oct	Wizz Air Malta
23 Sep - 03 Oct	easyJet
14 Sep - 01 Oct	Iberia Express
24 Sep - 01 Oct	easyJet
10 Sep - 13 Sep	Wizz Air
28 Sep - 03 Oct	Fly Play	direct
14 Sep - 20 Sep	Wizz Air Malta
16 Sep - 23 Sep	Ryanair
16 Sep - 24 Sep	Ryanair
10 Sep - 25 Sep	Wizz Air
14 Sep - 24 Sep	Wizz Air Malta
10 Sep - 23 Sep	Ryanair
11 Sep - 20 Sep	Wizz Air Malta
16 Sep - 30 Sep	Iberia Express
14 Sep - 23 Sep	Wizz Air Malta

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 174€

Return flights