Over a decade, researchers have depicted remarkable optoelectronic properties of halide-based organic–inorganic perovskites and demonstrated impressive power conversion efficiency in photovoltaic applications, starting from 3.9% to 26.1%. The optoelectronic properties of halide-based perovskites are significantly influenced by the crystal form and crystallization process. There are two common forms of halide-based perovskites: polycrystalline films and single-crystal. In polycrystalline thin films, multiple grain boundaries lead to ion migration, surface flaws, and instability, making them unsuitable for device applications. In contrast, single-crystal halide-based perovskites are stable and exhibit exceptional features like long carrier diffusion lengths and low trap density. Although research on polycrystalline halide-based perovskite thin films is currently intense, investigations on single crystals are still in their early stages. This review article discusses single-crystal perovskite halide growth methods and their use in optoelectronic devices, as crystal growth affects solar cells, light-emitting diodes, lasers, photodetectors, and other devices.