AirHint found the following cheapest return flights from Seoul (ICN) to Chiang Mai (CNX) in December 2025 (see full year).

Return flights

02 Dec - 15 Dec	Thai VietJet Air
10 Dec - 13 Dec	Air China
17 Dec - 24 Dec	Air China
01 Dec - 15 Dec	Air China
02 Dec - 08 Dec	Thai VietJet Air
01 Dec - 09 Dec	Air China
03 Dec - 09 Dec	Air China
01 Dec - 06 Dec	Air China
18 Dec - 22 Dec	Air China
01 Dec - 05 Dec	Air China
16 Dec - 14 Jan	HK Express
22 Dec - 16 Jan	Air China
16 Dec - 13 Jan	Air China
28 Dec - 27 Jan	Air China
27 Dec - 14 Jan	Air China
26 Dec - 06 Jan	Air China
30 Dec - 06 Jan	Air China
26 Dec - 01 Jan	Air China
28 Dec - 01 Jan	Air China
18 Dec - 03 Jan	Air China

Also check the deals for one-way flights from Seoul to Chiang Mai in December.

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 Chiang Mai in December from $286

Return flights