Halide perovskite derivatives with broad-spectrum emission have emerged as a promising candidate for next-generation single-source phosphor. However, most of the halide perovskite derivatives tend to emit warm-yellow emission and often lack long-life high-energy emission. In this study, a novel strategy based on “sterically hindered heterometallic polyhedral pairs” enables energy-transfer-enhanced singlet self-trapped exciton (¹STE) emission for realizing white emission. Through Sb³⁺ doping, [SbCl₅]²⁻-[MnCl₄]²⁻ polyhedral pairs effectively promote energy transfer from [MnCl₄]²⁻ to [SbCl₅]²⁻, resulting in a 3.6-fold increase in intensity of blue emission originating from ¹STEs of Sb³⁺, and a prolonged lifetime from nanoseconds to microseconds by three orders of magnitude. The CIE coordinate of (0.322, 0.377) closely matches standard white illumination. Mechanism studies reveal that the inter-polyhedral distance, overlap of density of states, and suitable energy band structures collectively facilitate energy transfer. Moreover, the white emissive halide perovskite derivative is successfully applied in a prototype white LED device, highlighting its potential for solid-state lighting. This work not only presents an effective structural design principle to realize white emission but also provides a new pathway to enhance the emission of singlet excitons, paving the way for development of high-performance lighting materials.