Linear dynamic range (LDR) and weak-light detection limit of photodetectors (PDs) directly determine the imaging resolution and signal-to-noise ratio (SNR) in weak-light condition. Herein, an all-inorganic perovskite PD is designed with a sandwich structure of NiOx/CsPbBr3/TiO2 (NCT). The CsPbBr3 perovskites are designed by a spin-coating method, and NiOx and TiO2 layers are introduced by an atomic layer deposition (ALD) method. The optimized NCT PD exhibits outstanding performance with ultralow dark current (approximate to 10(-11) A), broad LDR (186.7 dB), and ultralow detection limit (857 pW cm(-2)). Significantly, a proof-of-concept optical imaging system has been demonstrated using the NCT PD as the sensor element, which shows high resolution and high SNR even under weak-light condition. Furthermore, as a demo application, a solution is provided to the identification problem of 2D barcode under a weak-light environment as low as 4 nW cm(-2). The results show promising applications of the all-inorganic perovskite PD serving as a weak-light imaging sensor, with unique potential for low-cost manufacturing of large-area optoelectronic devices.