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

Return flights

01 Sep - 14 Sep	Thai AirAsia
08 Sep - 15 Sep	Thai AirAsia
26 Sep - 13 Oct	Thai Airways
28 Sep - 15 Oct	Thai Airways
28 Sep - 13 Oct	Thai Airways
07 Sep - 13 Sep	Thai Airways
05 Sep - 12 Sep	Thai Airways
06 Sep - 13 Sep	Thai Airways
01 Sep - 15 Sep	Thai Airways
08 Sep - 15 Sep	Korean Air	direct
15 Sep - 20 Sep	Thai Airways
25 Sep - 30 Sep	Thai Airways
28 Sep - 30 Sep	Thai Airways
26 Sep - 13 Oct	Korean Air	direct

Also check the deals for one-way flights from Kathmandu to Seoul 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 Kathmandu to Seoul in September from $521

Return flights