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

Return flights

23 Sep - 28 Sep	AJet	direct
24 Sep - 29 Sep	AJet	direct
24 Sep - 30 Sep	AJet	direct
23 Sep - 20 Oct	AJet	direct
22 Sep - 29 Sep	AJet	direct
18 Sep - 24 Sep	AJet	direct
09 Sep - 15 Sep	Air Serbia
09 Sep - 11 Sep	Air Serbia
09 Sep - 14 Sep	AJet	direct
09 Sep - 15 Sep	AJet	direct
26 Sep - 28 Sep	AJet	direct
30 Sep - 15 Oct	AJet
26 Sep - 03 Oct	AJet	direct
19 Sep - 04 Oct	AJet	direct
30 Sep - 15 Oct	Turkish Airlines	direct
22 Sep - 12 Oct	AJet
12 Sep - 04 Oct	AJet	direct
22 Sep - 12 Oct	AJet	direct

Also check the deals for one-way flights from Istanbul to Cologne 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 Istanbul to Cologne in September from $178

Return flights