The cheapest Belgrade to Ulaanbaatar return flight on the radar right now is €745, flying with Air Serbia + Turkish Airlines via one or more connections. It covers departures in November 2026, and every dated link below opens that exact BEG–ULN search on Skyscanner. Across 19 recorded checks it has ranged between €735 and €809. Our sampling points to November 2026 as the cheapest month to fly Belgrade to Ulaanbaatar.
Prices are re-checked against Skyscanner automatically, and every one shows when it was last confirmed, so nothing here is older than it looks. Not flying from Belgrade? We track 49 other departure cities for Ulaanbaatar, listed at the foot of this page.
Prices like this tend to vanish fast. If it has gone when you look, try the days either side of the dates above, since Belgrade to Ulaanbaatar is often still worth booking within a day or two of the fare we found.