Owing to their low trap-state density, high carrier mobility, and high thermal stability, CsPbBr3 perovskite microcrystals (MCs) have attracted significant attention for applications as photodetectors (PDs). However, solution synthesis processes lead to MC films with high void density, seriously limiting the performance of the PDs. Here, a pressure-assisted annealing strategy is introduced to significantly reduce the void density and decrease the surface roughness. The resulting self-powered all-inorganic CsPbBr3 perovskite MC thick-film PDs show improved performance characteristics, with responsivities and detectivities of up to 0.206 A W-1 and 7.23 × 1012 Jones, respectively. Moreover, the on/off ratios of the devices are up to 106, and the highest linear dynamic range reaches 123.5 dB. These improved results indicate that the pressure-assisted annealing method is an effective strategy to enhance the performance of solution-synthesized perovskite MC PDs.