In the title molecular salt, C11H13ClN3OS+·Br−, the C—N bond lengths in the –S–C(NH2)2 fragment indicate partial double-bond character of these bonds. The constituent ions are connected by N—H⋯Br bridges into Z-shaped chains. The supramolecular architecture of the structure can be described by being composed of these chains interlocked by additional C—H⋯Br short contacts. An intramolecular N—H⋯O=C bridge, as well as weak C—H⋯O hydrogen bonds, are also present in the structure