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

Return flights

04 Sep - 14 Sep	Fly Play	direct
11 Sep - 21 Sep	Fly Play	direct
28 Sep - 02 Oct	Fly Play	direct
18 Sep - 02 Oct	Fly Play	direct
11 Sep - 18 Sep	Fly Play	direct
04 Sep - 18 Sep	Fly Play	direct
18 Sep - 25 Sep	Fly Play	direct
04 Sep - 11 Sep	Fly Play	direct
04 Sep - 07 Sep	Fly Play	direct
14 Sep - 21 Sep	Fly Play	direct
18 Sep - 28 Sep	Fly Play	direct
25 Sep - 28 Sep	Fly Play	direct
29 Sep - 02 Oct	easyJet

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