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

Return flights

16 Sep - 18 Sep	China Eastern
16 Sep - 19 Sep	China Eastern
12 Sep - 19 Sep	China Eastern
20 Sep - 27 Sep	Jeju Air
08 Sep - 22 Oct	Air China
11 Sep - 26 Sep	Air India
09 Sep - 12 Sep	Air India
09 Sep - 22 Sep	Air India
09 Sep - 15 Sep	Air India
06 Sep - 13 Sep	Air India
10 Sep - 17 Sep	Jin Air
08 Sep - 13 Oct	Air China
13 Sep - 09 Oct	China Eastern
16 Sep - 01 Oct	Air India
18 Sep - 01 Oct	Air India
18 Sep - 02 Oct	Air India
18 Sep - 03 Oct	Air India
16 Sep - 02 Oct	Air India
26 Sep - 03 Oct	Air China
08 Sep - 17 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 326€

Return flights