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

Return flights

11 Dec - 08 Jan	Thai VietJet Air
25 Dec - 07 Jan	Thai AirAsia
23 Dec - 07 Jan	Etihad Airways
11 Dec - 31 Dec	Etihad Airways
23 Dec - 15 Jan	Air China
24 Dec - 15 Jan	Air China
18 Dec - 08 Jan	Air China
21 Dec - 08 Jan	Air China
23 Dec - 08 Jan	Air China
22 Dec - 30 Dec	Thai VietJet Air
20 Dec - 03 Jan	Etihad Airways
21 Dec - 03 Jan	Etihad Airways
25 Dec - 31 Dec	China Southern
21 Dec - 27 Dec	Bangkok Airways
15 Dec - 21 Dec	Air China
22 Dec - 27 Dec	Thai VietJet Air
07 Dec - 13 Dec	China Southern
06 Dec - 13 Dec	China Southern

Also check the deals for one-way flights from Chiang Mai to London 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 Chiang Mai to London in December from $661

Return flights