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

Return flights

25 Sep - 02 Oct	Fly Play	direct
18 Sep - 02 Oct	Fly Play	direct
11 Sep - 21 Sep	Fly Play	direct
22 Sep - 24 Sep	easyJet
25 Sep - 05 Oct	easyJet
11 Sep - 18 Sep	Fly Play	direct
04 Sep - 11 Sep	Fly Play	direct
28 Sep - 05 Oct	Fly Play	direct
25 Sep - 05 Oct	Fly Play	direct
20 Sep - 28 Sep	easyJet
04 Sep - 14 Sep	Fly Play	direct
04 Sep - 18 Sep	Fly Play	direct
27 Sep - 04 Oct	easyJet
02 Sep - 14 Sep	Ryanair
14 Sep - 18 Sep	Fly Play	direct
18 Sep - 28 Sep	Fly Play	direct
21 Sep - 05 Oct	Fly Play	direct

Also check the deals for one-way flights from Porto 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 Porto to Keflavik in September from 225€

Return flights