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

Return flights

17 Sep - 02 Oct	Wizz Air Malta
16 Sep - 02 Oct	Iberia Express
16 Sep - 24 Sep	Iberia Express
17 Sep - 25 Sep	Wizz Air Malta
18 Sep - 25 Sep	Wizz Air Malta
17 Sep - 23 Sep	Wizz Air Malta
18 Sep - 23 Sep	Wizz Air Malta
16 Sep - 25 Sep	Iberia Express
24 Sep - 30 Sep	Wizz Air Malta
24 Sep - 01 Oct	Ryanair
13 Sep - 23 Sep	Iberia Express
14 Sep - 30 Sep	Iberia Express
13 Sep - 24 Sep	Iberia Express
30 Sep - 07 Oct	Wizz Air Malta
17 Sep - 01 Oct	Wizz Air Malta
26 Sep - 02 Oct	Ryanair
26 Sep - 07 Oct	Ryanair
27 Sep - 08 Oct	Ryanair
26 Sep - 08 Oct	Ryanair
25 Sep - 01 Oct	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 163€

Return flights