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

Return flights

25 Sep - 02 Oct	KLM
18 Sep - 24 Sep	KLM
16 Sep - 23 Sep	Pegasus Airlines
17 Sep - 26 Sep	KLM
25 Sep - 09 Oct	KLM
17 Sep - 24 Sep	KLM
17 Sep - 02 Oct	KLM
23 Sep - 07 Oct	Wizz Air UK
20 Sep - 23 Sep	Pegasus Airlines
22 Sep - 27 Sep	KLM
16 Sep - 20 Sep	Pegasus Airlines
23 Sep - 30 Sep	Wizz Air UK
20 Sep - 30 Sep	AJet
29 Sep - 03 Oct	Wizz Air UK
29 Sep - 06 Oct	Wizz Air UK
23 Sep - 27 Sep	Wizz Air UK
20 Sep - 01 Oct	Pegasus Airlines
15 Sep - 22 Oct	Wizz Air UK
15 Sep - 19 Oct	Wizz Air UK
06 Sep - 05 Oct	Wizz Air UK

Also check the deals for one-way flights from Istanbul 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 Istanbul to Keflavik in September from 198€

Return flights