Doping semiconductor nanocrystals and integrating disparate components together are two effective ways for modulating the optical properties of semiconductor nanocrystals. For the first time, we successfully synthesized Mn-doped Ag₂S-ZnS heteronanostructures (HNSs) by combining these two strategies together. The obtained Mn-doped Ag₂S-ZnS HNSs exhibit multicolor emissions of blue, orange, and near-infrared (NIR), in which the blue emission originates from ZnS trap state, the orange emission is induced by the ⁴T₁–⁶A₁ transition in Mn²⁺ dopant, and the NIR emission is attributed to the band gap emission of Ag₂S. Reaction temperature-dependent and Mn²⁺ dopant concentration-dependent optical properties, as well as the growth kinetics of Ag₂S-ZnS HNSs during doping process, were systemically studied to achieve the desirable optical properties and preserve well-defined HNSs simultaneously. We expect that the prepared Mn-doped Ag₂S-ZnS HNSs with tunable multicolor emissions will create numerous opportunities for potential applications in bioimaging and optoelectronic devices, and the facile methodology modulating Ag₂S-ZnS HNSs with desirable properties will be general and be ready to other complex semiconductor nanostructures.