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

Return flights

18 Sep - 23 Sep	Jin Air
03 Sep - 10 Sep	Korean Air
03 Sep - 11 Sep	Jeju Air
10 Sep - 25 Sep	Jeju Air
24 Sep - 25 Sep	Jeju Air
10 Sep - 12 Sep	Jeju Air
23 Sep - 25 Sep	Jeju Air
23 Sep - 29 Sep	Jeju Air
27 Sep - 29 Sep	Jeju Air
28 Sep - 01 Oct	Jeju Air
24 Sep - 28 Sep	Jeju Air
27 Sep - 02 Oct	Jeju Air
17 Sep - 16 Oct	Jeju Air
26 Sep - 02 Oct	Jeju Air
09 Sep - 26 Oct	Jeju Air
28 Sep - 05 Oct	Air Busan
03 Sep - 15 Oct	EVA Air
20 Sep - 02 Oct	Air China
27 Sep - 14 Oct	Jeju Air
20 Sep - 01 Oct	Jeju Air

Also check the deals for one-way flights from Seoul to Bangkok 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 Bangkok in September from 222€

Return flights