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

Return flights

12 Sep - 20 Sep	Thai AirAsia
12 Sep - 19 Sep	Thai AirAsia
08 Sep - 20 Sep	Thai AirAsia
08 Sep - 19 Sep	Thai AirAsia
16 Sep - 20 Sep	Thai AirAsia
16 Sep - 19 Sep	Thai AirAsia
10 Sep - 20 Sep	Thai AirAsia
10 Sep - 19 Sep	Thai AirAsia
12 Sep - 25 Sep	Thai AirAsia
07 Sep - 20 Sep	Thai AirAsia
16 Sep - 05 Oct	Thai AirAsia
30 Sep - 08 Oct	Thai AirAsia
30 Sep - 05 Oct	Thai AirAsia

Also check the deals for one-way flights from Chiang Mai 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 Chiang Mai to Kathmandu in September from 329€

Return flights