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

Return flights

21 Sep - 11 Oct	Ryanair
03 Sep - 07 Sep	Ryanair
09 Sep - 16 Sep	Ryanair
02 Sep - 08 Sep	Ryanair
01 Sep - 14 Sep	Eurowings
01 Sep - 10 Sep	Eurowings
05 Sep - 18 Sep	Eurowings
30 Sep - 08 Oct	AJet
02 Sep - 06 Sep	Ryanair
21 Sep - 28 Sep	Ryanair
22 Sep - 26 Sep	Ryanair
29 Sep - 06 Oct	Turkish Airlines
30 Sep - 06 Oct	AJet
03 Sep - 14 Sep	Ryanair
29 Sep - 18 Oct	Turkish Airlines
29 Sep - 07 Oct	Turkish Airlines
30 Sep - 07 Oct	Eurowings

Also check the deals for one-way flights from Cologne to Seoul 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 Seoul in September from $679

Return flights