In the title compound, C12H12N3O2+·Br−, the bromide anion and most atoms of the cation lie on a mirror plane. In the cation, the pyridine and benzene rings are almost orthogonal to each other, forming a dihedral angle of 89.2 (1)°. The crystal packing is stabilized by weak N—H⋯Br and C—H⋯O intermolecular hydrogen bonds.