Effective Mn²⁺ doping in a CsPbCl₃ lattice utilizing manganese acetate and trimethylchlorosilane is achieved via a one-pot hot-injection synthesis method. This strongly contrasts to the previous case, where only the MnCl₂ precursor was suitable for Mn²⁺ doping by considering the matching of bond dissociation energies between Mn–Cl and Pb–Cl. The Mn doping concentration and luminescence quantum yield are highly dependent on trimethylchlorosilane content. A new doping mechanism is proposed, where the incorporation of Mn²⁺ into CsPbCl₃ is achieved via directly inserting [MnCl₆]⁴⁻ octahedra into the perovskite structure during the nucleation/growth processes instead of Mn-to-Pb cation exchange. Accordingly, increasing Cl⁻ content in the reaction solution indeed promotes the doping of other divalent transition metal ions such as Ni²⁺, Cu²⁺ and Zn²⁺ in CsPbCl₃ and improve the quantum yield of CsPbCl₃ nanocrystals up to ∼20% compared to the undoped counterparts (∼1%).