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

Return flights

22 Sep - 30 Sep	Ryanair
03 Sep - 07 Sep	Norwegian
24 Sep - 13 Oct	Norwegian	direct
03 Sep - 22 Sep	Norwegian
03 Sep - 10 Sep	Norwegian
10 Sep - 22 Sep	Norwegian
24 Sep - 06 Oct	Norwegian	direct
24 Sep - 15 Oct	Norwegian	direct
22 Sep - 29 Sep	Ryanair
12 Sep - 16 Sep	easyJet
25 Sep - 29 Sep	Ryanair
24 Sep - 08 Oct	Norwegian
24 Sep - 29 Sep	Norwegian
10 Sep - 29 Sep	Norwegian
22 Sep - 01 Oct	Ryanair
17 Sep - 06 Oct	Norwegian	direct
24 Sep - 01 Oct	Norwegian	direct
24 Sep - 08 Oct	Norwegian	direct
24 Sep - 10 Oct	Norwegian	direct
10 Sep - 01 Oct	Norwegian	direct

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 $184

Return flights