AirHint found the following cheapest return flights from Sydney (SYD) to Ulaanbaatar (UBN) in September 2025 (see full year).

Return flights

09 Sep - 16 Sep	VietJet Air
09 Sep - 15 Sep	Air China
09 Sep - 22 Sep	T'way Air
18 Sep - 26 Sep	T'way Air
27 Sep - 03 Oct	Air China
12 Sep - 16 Sep	Qantas
19 Sep - 21 Sep	Cathay Pacific
08 Sep - 10 Oct	Cathay Pacific
30 Sep - 06 Oct	Air China
26 Sep - 10 Oct	Cathay Pacific
28 Sep - 03 Oct	Cathay Pacific
27 Sep - 04 Oct	Cathay Pacific
27 Sep - 05 Oct	Cathay Pacific
18 Sep - 10 Oct	Air China
09 Sep - 06 Oct	Condor

Also check the deals for one-way flights from Sydney to Ulaanbaatar 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 Sydney to Ulaanbaatar in September from 631€

Return flights