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

Return flights

29 Sep - 13 Oct	Ryanair
30 Sep - 07 Oct	Ryanair
29 Sep - 13 Oct	Eurowings	direct
27 Sep - 30 Sep	Ryanair
23 Sep - 30 Sep	Ryanair
25 Sep - 09 Oct	Eurowings	direct
29 Sep - 07 Oct	Ryanair
27 Sep - 11 Oct	Ryanair
29 Sep - 01 Oct	Ryanair
29 Sep - 30 Sep	Ryanair
27 Sep - 11 Oct	Eurowings	direct
25 Sep - 14 Oct	Eurowings
25 Sep - 14 Oct	Ryanair	direct
25 Sep - 30 Sep	Ryanair
23 Sep - 25 Sep	Ryanair
23 Sep - 29 Sep	Ryanair
28 Sep - 30 Sep	Ryanair
25 Sep - 29 Sep	Eurowings
26 Sep - 30 Sep	Ryanair
21 Sep - 23 Sep	Ryanair

Also check the deals for one-way flights from Cologne to Porto 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 Cologne to Porto in September from 137€

Return flights