Sensory adaptation is an essential part of biological neural systems for sustaining human life. Using the light-induced halide phase segregation of CsPb(Br<sub>1-<i>x</i></sub>I<sub><i>x</i></sub>)<sub>3</sub> perovskite, we introduce neuromorphic phototransistors that emulate human sensory adaptation. The phototransistor based on a hybrid structure of perovskite and transition-metal dichalcogenide (TMD) emulates the sensory adaptation in response to a continuous light stimulus, similar to the neural system. The underlying mechanism for the sensory adaptation is the halide segregation of the mixed halide perovskites. The phase separation under visible-light illumination leads to the segregation of I and Br into separate iodide- and bromide-rich domains, significantly changing the photocurrent in the phototransistors. The devices are reversible upon the removal of the light stimulation, resulting in near-complete recovery of the photosensitivity before the phase segregation (sensitivity recovery of 96.65% for 5 min rest time). The proposed phototransistor based on the perovskite-TMD hybrid structure can be applied to other neuromorphic devices such as neuromorphic photonic devices, intelligent sensors, and selective light-detecting image sensors.