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

Return flights

10 Sep - 22 Sep	Norwegian
29 Sep - 20 Oct	Ryanair
10 Sep - 16 Sep	Norwegian
24 Sep - 25 Sep	Norwegian
05 Sep - 09 Sep	Norwegian
16 Sep - 23 Sep	Vueling Airlines
17 Sep - 22 Sep	Ryanair
22 Sep - 24 Oct	Ryanair
19 Sep - 22 Sep	Ryanair
19 Sep - 24 Oct	Ryanair
17 Sep - 21 Sep	Ryanair
03 Sep - 17 Sep	Norwegian
10 Sep - 17 Sep	Norwegian
29 Sep - 31 Oct	Ryanair
24 Sep - 13 Oct	Norwegian	direct
24 Sep - 11 Oct	Norwegian
29 Sep - 06 Oct	Ryanair
24 Sep - 15 Oct	Norwegian	direct
24 Sep - 06 Oct	Norwegian
15 Sep - 06 Oct	Ryanair

Also check the deals for one-way flights from Porto to Oslo 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 Oslo in September from 141€

Return flights