The asymmetric unit of the title compound, [Co(NH3)6][Mn(CN)6], contains one Co and one Mn atom, both lying on threefold inversion axes, and one NH3 and one CN group. The octahedral environments around CoII and MnII are generated by symmetry and show very slight deviations from ideal geometry. A three-dimensional network is created by N—H⋯N hydrogen bonds