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
03 Sep - 07 Sep	SriLankan Airlines
03 Sep - 14 Sep	SriLankan Airlines
10 Sep - 14 Sep	SriLankan Airlines
10 Sep - 21 Sep	SriLankan Airlines
01 Sep - 09 Sep	Air China
05 Sep - 09 Sep	Air China
03 Sep - 09 Sep	Air China
06 Sep - 09 Sep	Air China
02 Sep - 09 Sep	Air China
13 Sep - 03 Oct	Air China
26 Sep - 24 Oct	Thai AirAsia X
08 Sep - 01 Oct	Thai Airways
01 Sep - 01 Oct	Thai Airways
10 Sep - 22 Oct	Thai Airways
20 Sep - 04 Oct	Thai Airways
16 Sep - 19 Oct	Thai Airways
05 Sep - 13 Oct	Thai Airways
25 Sep - 14 Oct	Air China
25 Sep - 16 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 273€

Return flights