AirHint found the following cheapest return flights from Seoul (GMP) to Ulaanbaatar (UBN) in December 2025 (see full year).

Return flights

03 Dec - 07 Dec	Air China
31 Dec - 04 Jan	Air China
15 Dec - 22 Dec	Air China
22 Dec - 26 Dec	Air China
26 Dec - 04 Jan	Air China
24 Dec - 30 Dec	Air China
31 Dec - 03 Jan	Air China
26 Dec - 31 Dec	Air China
12 Dec - 17 Dec	Air China
21 Dec - 31 Dec	Air China
10 Dec - 12 Dec	Air China
07 Dec - 14 Dec	Air China

Also check the deals for one-way flights from Seoul to Ulaanbaatar 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 Ulaanbaatar in December from 242€

Return flights