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

Return flights

21 Sep - 29 Sep	Wizz Air Malta
22 Sep - 01 Oct	Fly Play
10 Sep - 15 Sep	Fly Play
25 Sep - 30 Sep	Wizz Air Malta
15 Sep - 17 Sep	Fly Play
08 Sep - 14 Sep	Fly Play
11 Sep - 15 Sep	KLM
22 Sep - 29 Sep	Fly Play
11 Sep - 14 Sep	Fly Play
07 Sep - 14 Sep	KLM
24 Sep - 27 Sep	easyJet
26 Sep - 06 Oct	easyJet
26 Sep - 01 Oct	easyJet
26 Sep - 06 Oct	Fly Play	direct
22 Sep - 01 Oct	Icelandair	direct
26 Sep - 01 Oct	Fly Play	direct

Also check the deals for one-way flights from Keflavik to Barcelona 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 Barcelona in September from $269

Return flights