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

Return flights

29 Sep - 13 Oct	IndiGo
29 Sep - 20 Oct	IndiGo
30 Sep - 12 Oct	IndiGo
30 Sep - 13 Oct	IndiGo
30 Sep - 10 Oct	IndiGo
30 Sep - 09 Oct	IndiGo
30 Sep - 14 Oct	MIAT Mongolian Airlines
28 Sep - 12 Oct	IndiGo
27 Sep - 10 Oct	IndiGo
27 Sep - 12 Oct	IndiGo
25 Sep - 28 Sep	IndiGo
26 Sep - 30 Sep	IndiGo
25 Sep - 29 Sep	IndiGo
22 Sep - 28 Sep	IndiGo
25 Sep - 30 Sep	IndiGo
26 Sep - 29 Sep	IndiGo
24 Sep - 28 Sep	IndiGo
21 Sep - 27 Sep	IndiGo
23 Sep - 28 Sep	IndiGo
21 Sep - 25 Sep	IndiGo

Also check the deals for one-way flights from Istanbul 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 Istanbul to Seoul in September from 401€

Return flights