Moisture-delicate and water-unstable organic-inorganic halide perovskites (OI-HPs) create huge challenges for the synthesis of highly efficient water-stable light-emitting materials for optoelectronic devices. Herein, a simple acid solution-assisted method to synthesize quantum confined 2D lead perovskites through Mn doping is reported. The efficient energy transfer between host and dopant ions in orange light-emitting Mn2+-doped OI-HPs leads to the most efficient integrated luminescence with a photoluminescence quantum yield over 45%. The Mn2+ substitution of Pb2+ and passivation with low dielectric constant molecules such as phenethylamine, benzylamine, and butylamine enhance water resistivity, leading to water stability. The dual emission process of this water-stable 2D Mn-doped perovskite will help in developing highly efficient 2D water-stable perovskites for practical applications.