We demonstrate enhanced performance of solution-processed photodetectors composed of all-inorganic CsPbBr3 perovskite films with ZnO nanoparticles (NPs) decoration. Introducing ZnO NPs into CsPbBr3 precursor solution results in the film with more uniformly and compactly distributed crystalline grains. ZnO NPs can also promote the transport of photon-generated carriers from the central CsPbBr3 absorption layer to the lateral electrodes. Meanwhile, the asymmetry electrodes, i.e., indium tin oxide and silver, of the photodetectors create a built-in electric field driving the photodetectors operation without external bias voltage. Compared to the photodetectors without ZnO decoration, the fabricated all-inorganic CsPbBr3:ZnO photodetectors achieve a comparable rise time of 0.409 s, a fall time of 17.92 ms, and an on/off ratio of 12.86 without external bias source.