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

Return flights

06 Dec - 11 Dec	HK Express
18 Dec - 15 Jan	Vietnam Airlines
06 Dec - 10 Dec	HK Express
01 Dec - 15 Dec	Vietnam Airlines
11 Dec - 08 Jan	Vietnam Airlines
01 Dec - 12 Dec	HK Express
16 Dec - 21 Jan	VietJet Air
08 Dec - 11 Dec	HK Express
01 Dec - 06 Dec	HK Express
10 Dec - 15 Dec	HK Express
08 Dec - 12 Dec	HK Express
08 Dec - 13 Dec	HK Express
16 Dec - 19 Jan	VietJet Air
16 Dec - 17 Jan	VietJet Air
16 Dec - 18 Jan	VietJet Air
16 Dec - 07 Jan	VietJet Air
05 Dec - 14 Dec	VietJet Air
17 Dec - 19 Jan	VietJet Air
16 Dec - 16 Jan	VietJet Air
16 Dec - 22 Jan	VietJet Air

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 $258

Return flights