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

Return flights

25 Sep - 02 Oct	Wizz Air Malta
21 Sep - 25 Sep	Wizz Air Malta
17 Sep - 25 Sep	Wizz Air Malta
04 Sep - 07 Sep	Wizz Air Malta
28 Sep - 05 Oct	Wizz Air Malta
20 Sep - 25 Sep	Ryanair
18 Sep - 25 Sep	Wizz Air Malta
16 Sep - 01 Oct	easyJet
14 Sep - 25 Sep	Wizz Air Malta
21 Sep - 03 Oct	Wizz Air Malta
15 Sep - 25 Sep	Iberia
20 Sep - 02 Oct	Ryanair
10 Sep - 24 Sep	easyJet
11 Sep - 18 Sep	Wizz Air Malta
23 Sep - 02 Oct	Iberia
05 Sep - 07 Sep	Ryanair
25 Sep - 01 Oct	Wizz Air Malta
30 Sep - 08 Oct	easyJet
24 Sep - 01 Oct	Wizz Air Malta
20 Sep - 05 Oct	Ryanair

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.

Book a cheap hotel in Keflavik

Cheap car rent in Keflavik

Cheapest return flights from Madrid to Keflavik in September from 128€

Return flights