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

Return flights

25 Sep - 16 Oct	Ryanair	direct
04 Sep - 18 Sep	Eurowings	direct
11 Sep - 18 Sep	Eurowings	direct
04 Sep - 11 Sep	Eurowings	direct
26 Sep - 16 Oct	Ryanair	direct
02 Sep - 18 Sep	Ryanair
06 Sep - 11 Sep	Eurowings	direct
13 Sep - 18 Sep	Ryanair
09 Sep - 11 Sep	Ryanair
29 Sep - 09 Oct	Ryanair
25 Sep - 02 Oct	Ryanair
25 Sep - 10 Oct	Ryanair
25 Sep - 11 Oct	Ryanair
30 Sep - 02 Oct	Ryanair
26 Sep - 09 Oct	Ryanair	direct
05 Sep - 11 Sep	Ryanair
25 Sep - 30 Sep	Ryanair
25 Sep - 25 Sep	Ryanair
18 Sep - 02 Oct	Eurowings
25 Sep - 09 Oct	Ryanair	direct

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 109€

Return flights