Metal halide perovskite has attracted enhanced interest for its diverse electronic and optoelectronic applications. However, the fabrication of micro‐ or nanoscale crystalline perovskite functional devices remains a great challenge due to the fragility, solvent, and heat sensitivity of perovskite crystals. Here, a strategy is proposed to fabricate electronic and optoelectronic devices by directly growing perovskite crystals on microscale metallic structures in liquid phase. The well‐contacted perovskite/metal interfaces ensure these heterostructures serve as high‐performance field effect transistors (FETs) and excellent photodetector devices. When serving as an FET, the on/off ratio is as large as 106 and the mobility reaches up to ≈2.3 cm2 V−1 s−1. A photodetector is displayed with high photoconductive switching ratio of ≈106 and short response time of ≈4 ms. Furthermore, the photoconductive response is proved to be band‐bending‐assisted separation of photoexcited carriers at the Schottky barrier of the silver and p‐type perovskites.