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

Return flights

03 Sep - 14 Sep	SriLankan Airlines
03 Sep - 07 Sep	SriLankan Airlines
06 Sep - 10 Sep	Air China
04 Sep - 19 Sep	Sichuan Airlines
06 Sep - 09 Sep	Air China
01 Sep - 12 Sep	Air China
01 Sep - 15 Sep	Air China
01 Sep - 06 Sep	Air China
06 Sep - 17 Sep	Air China
20 Sep - 27 Sep	China Eastern
19 Sep - 24 Oct	Air China
19 Sep - 20 Oct	Air China
13 Sep - 17 Oct	Thai Airways
17 Sep - 15 Oct	Thai Airways
18 Sep - 19 Oct	Thai Airways
16 Sep - 20 Oct	Thai Airways
30 Sep - 18 Oct	Air China
15 Sep - 13 Oct	Thai Airways
19 Sep - 28 Oct	Air China
22 Sep - 24 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 $341

Return flights