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

Return flights

03 Sep - 06 Sep	China Southern
18 Sep - 21 Sep	Air China
03 Sep - 09 Sep	China Southern
11 Sep - 17 Sep	Air China
10 Sep - 13 Sep	China Southern
10 Sep - 20 Sep	China Southern
18 Sep - 26 Sep	Air China
20 Sep - 26 Sep	Air China
18 Sep - 28 Sep	Air China
20 Sep - 26 Oct	Air China
16 Sep - 22 Oct	Air China
08 Sep - 18 Sep	China Southern
18 Sep - 24 Oct	Air China
17 Sep - 23 Oct	China Southern
15 Sep - 21 Oct	China Southern
19 Sep - 23 Oct	China Southern
16 Sep - 03 Oct	Air China
19 Sep - 25 Oct	China Southern
17 Sep - 25 Oct	China Southern
20 Sep - 24 Oct	Air China

Also check the deals for one-way flights from Seoul to Istanbul 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 Seoul to Istanbul in September from 439€

Return flights