Large-size single crystal (SCs) is an excellent platform for studying the optoelectronic properties of materials. However, growing high-quality crystals has always been a challenge. Here we develop a liquid-induced diffusion (LDSC) method for high-efficiency and low-cost growth of centimeter-sized Cs4PbBr6 crystals. All-sized crystals with a special diamond-like appearance exhibit strong green photoluminescence (PL) and good stability. In addition, X-ray diffraction (XRD) reveals that the diamond-like Cs4PbBr6 crystal exhibits a different crystal surface orientation from the rhombic SCs. More importantly, different from the CsPbBr3 impurity-induced photoluminescence mechanism, the strong green PL of the as-prepared diamond-like Cs4PbBr6 crystal originates from its defect state: Br vacancies (VBr). Furthermore, high-efficiency white light-emitting diodes (WLED) devices are prepared by using high-luminous intensity Cs4PbBr6 crystals as green light emitters. The optimized devices generate high-quality white light with luminous efficiency of ∼54 lm W−1, which is much better than that of conventional perovskite nanocrystals-based LED devices. Our work demonstrates that the Cs4PbBr6 crystal devices possess higher luminous efficiency, better stability and great application potential in display backlighting.