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

Return flights

08 Sep - 15 Sep	China Eastern
12 Sep - 22 Sep	China Eastern
09 Sep - 19 Sep	China Southern
12 Sep - 28 Sep	China Eastern
17 Sep - 24 Sep	Jeju Air
20 Sep - 27 Sep	Jeju Air
15 Sep - 02 Oct	China Eastern
09 Sep - 17 Sep	Air India
11 Sep - 19 Sep	Air India
11 Sep - 22 Sep	Air India
12 Sep - 15 Sep	China Southern
07 Sep - 03 Oct	Air India
18 Sep - 04 Oct	Air India
12 Sep - 01 Oct	China Southern
16 Sep - 01 Oct	Air India
18 Sep - 02 Oct	Air India
23 Sep - 17 Oct	Eastar Jet
28 Sep - 25 Oct	Air China
30 Sep - 22 Oct	Air China
25 Sep - 25 Oct	Air China

Also check the deals for one-way flights from Seoul to Kathmandu 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 Kathmandu in September from $383

Return flights