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

Return flights

03 Sep - 07 Sep	SriLankan Airlines
03 Sep - 14 Sep	SriLankan Airlines
10 Sep - 21 Sep	SriLankan Airlines
07 Sep - 12 Oct	Vietnam Airlines
02 Sep - 04 Sep	Air China
02 Sep - 07 Sep	Air China
02 Sep - 11 Sep	Air China
01 Sep - 29 Sep	Air China
01 Sep - 16 Sep	Air China
02 Sep - 14 Sep	Air China
04 Sep - 09 Sep	Air China
28 Sep - 31 Oct	China Eastern
29 Sep - 11 Oct	Thai AirAsia X
30 Sep - 14 Oct	Air China
19 Sep - 24 Oct	Air China
08 Sep - 03 Oct	Thai Airways
29 Sep - 17 Oct	Air China
08 Sep - 13 Oct	Thai Airways
21 Sep - 12 Oct	Thai Airways
22 Sep - 03 Oct	Thai Airways

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 290€

Return flights