Abstract: Lead halide perovskites have received increasing attention recently as a candidate material in various optoelectronic areas because of their high performance as light absorbers. Herein, we report the growth of CsPbI₃ nanobelts via a solution process. A single-crystalline CsPbI₃ nanobelt with uniform morphology can be achieved by controlling the amount of PbI₂. A single-crystalline CsPbI₃ nanobelt possesses a mean width, length, and thickness of 100 nm, 5 µm, and 20 nm, respectively. In this work, photodetectors (PDs) based on individual CsPbI₃ nanobelts are constructed and found to perform well with an external quantum efficiency and responsivity of 2.39 × 10⁵% and 770 A/W, respectively. The PDs also show a high detectivity of up to 3.12 × 10¹² Jones, which is at par with that of Si PDs. The PDs developed in this work exhibit great promise in various optoelectronic nanodevices.