A new tetranuclear cuprous halide complex, (CuBr)₄(PN)₂ (PN = 2-(diphenylphosphaneyl)- 6-methoxypyridine), was synthesized and fully characterized. In solid state, this complex exhibits efficient blue emission with a photoluminescence quantum yield of 43.3% and a decay time of 19 μs at room temperature. The theoretical calculations, combined with the temperature dependence of spectroscopic properties and emission decay behaviors, indicate that the emission in the solid state originates from the ^{1, 3}(MLCT + XLCT) excited states, which are in thermal equilibrium with a small energy gap of about 0.1 eV.