Bulgan (Mongolian: Булган) is one of the 21 aimags (provinces) of Mongolia, located in northern Mongolia. Its capital is also named Bulgan.

The aimag is surrounded by Russia (Buryatia) in the north, the aimags Khövsgöl in the northwest, Arkhangai in the southwest, Övörkhangai in the south, Töv in the southeast, and Selenge in the northeast. The small Orkhon Aimag forms an enclave at the border to Selenge.

The north of the aimag is characterized by alpine forests, gradually blending in the arid steppe plains of the central Mongolian highland. The main rivers are the Orkhon and the Selenge, both of which enter the aimag from Övörkhangai. As a result, southern Bulgan is one of Mongolia’s few arable regions.