The development of melt-quenched organic-inorganic metal halide (OIMH) glasses is hampered by the scarcity of suitable organic molten salts and low luminescence efficiency. Herein, we developed a series of two-component OIMH amorphous glasses consisting of (TPG) 2 MnBr 4 (TPG + , triphenylguanidium) and A 2 MnBr 4 (A, organic molten cation), named α G (A x TPG y ). The high glass-formation ability (GFA) in (TPG) 2 MnBr 4 provides a platform to modulate the crystallization of another molten A 2 MnBr 4 by homogeneous melting. Moreover, the GFA modulation allows controlled in situ crystallization of α G (A x TPG y ) and the formation of transparent glass-crystal composites with higher luminescence efficiency. For instance, the light yield of α G (PTP 99 TPG 1 ) (PTP + , propyltriphenylphosphonium) is improved from 18,800 to 35,140 photons per mega–electron volt after annealing at 55°C, showing huge application potentials in radiation detection and high-resolution x-ray imaging. The present research would inspire further exploration of high-performance OIMH glasses and facilitate multiple applications in advanced photonics such as scintillators, photoconductive fibers, light-emitting diodes, and laser crystals.