Metal-halide perovskite nanocrystals (NCs) are considered to be promising types of optoelectronic and photonic materials. The emission colors of the cesium lead halide perovskite (CsPbX₃, X = Cl, Br, I) NCs depend on the joint influence of the emission peaks of the host and its dopant ions. Herein, we report a phosphine-free strategy to synthesize Mn-doped CsPb(Cl/Br)₃ NCs to tune their optical properties in a wide color gamut. Colloidal Mn-doped CsPb(Cl/Br)₃ NCs were synthesized by injecting Cs-oleate solution into the MnCl₂ and PbBr₂ precursor solution. The as-prepared Mn-doped CsPb(Cl/Br)₃ NCs are highly crystalline and uniform sized nanocubes with two emission peaks, including the host emission around 450 nm and the Mn²⁺ dopant emission around 600 nm, which are sensitive to the MnCl₂-to-PbBr₂ molar feed ratio and the reaction temperature. By varying the MnCl₂-to-PbBr₂ molar feed ratio or the reaction temperature, the relative PL intensities of dual color emission can be manipulated, showing their ability in tunable color output.