Zero-dimensional (0D) Mn-based metal halides used as luminescent materials and scintillators have become a research hotspot in the field of photoelectric materials and devices due to their unique composition, structure, and fluorescence properties. It is of great value to explore new Mn-based metal halides to achieve multifunctional applications. Herein, the novel 0D Mn-based metal halide single crystal (BPTP)MnBr is synthesized by a simple solvent-antisolvent recrystallization method. Under excitation at 468 nm, the (BPTP)MnBr single crystal shows a pronounced narrow-band green luminescence centered at 515 nm derived from the - transition of the Mn ion. This emission has a relatively narrow full width at half maximum of 43 nm and a high photoluminescence quantum yield (PLQY) of 82%. In addition, (BPTP)MnBr exhibits good thermal stability at 393 K with a retention of 79% of the initial photoluminescence intensity at 298 K. Benefiting from its strong blue light excitation, high PLQY, and good thermal stability, we manufacture an ideal white light-emitting diode (LED) device using a 460 nm blue LED chip, green-emitting (BPTP)MnBr, and commercial KSiF:Mn red phosphor. Under 20 mA drive current, the LED shows a high luminous efficiency of 112 lm/W and a wide color gamut of 110.8%, according to the National Television System Committee standard. In addition, (BPTP)MnBr crystals show a strong X-ray absorption. Based on the commercial LuAlO:Ce scintillator, the calculated light yield of (BPTP)MnBr reaches up to about 136,000 photons/MeV and the detection limit reaches 0.282 μGy s. Additionally, a melt quenching approach is used to construct a (BPTP)MnBr clear glass scintillation screen, realizing a spatial resolution of 10.1 lp/mm. The proper performances of (BPTP)MnBr as phosphor-converted LED materials and the X-ray scintillator with the addition of eco-friendly, low-cost solution processability make 0D Mn-based metal halides potential luminescent materials for multifunctional applications.