We report a MAPbI3-based self-powered photodetector (SPPD). It has a dual sensing mechanism that relies on the joint properties of a photoelectric effect and a triboelectric effect of the perovskite material. Both the photoconductivity and the surface triboelectric density of the MAPbI3-based composite thin film are significantly altered upon solar illumination, which results in considerable reduction of the output voltage. The SPPD exhibits excellent responsivity (7.5 V W(-1)), rapid response time (<80 ms), great repeatability, and broad detection range that extends from UV to visible regions. This work presents a route to designing high-performance self-powered photodetectors from the aspect of materials.