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

Return flights

16 Sep - 24 Sep	easyJet
14 Sep - 21 Sep	Fly Play	direct
11 Sep - 14 Sep	Fly Play	direct
04 Sep - 14 Sep	Fly Play	direct
04 Sep - 07 Sep	Fly Play	direct
25 Sep - 28 Sep	Fly Play	direct
04 Sep - 18 Sep	Fly Play	direct
04 Sep - 11 Sep	Fly Play	direct
18 Sep - 21 Sep	Fly Play	direct
28 Sep - 05 Oct	Fly Play	direct
17 Sep - 23 Sep	Ryanair
25 Sep - 02 Oct	Fly Play	direct
28 Sep - 02 Oct	Fly Play	direct
18 Sep - 02 Oct	Fly Play	direct
26 Sep - 04 Oct	Volotea
27 Sep - 04 Oct	easyJet
25 Sep - 05 Oct	Ryanair

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 $184

Return flights