Printed flexible photodetectors based on 2D inorganic perovskites with atomic thickness show excellent photosensing with fast rise and decay response times. As‐synthesized nanosheets can easily be dispersed in various solvents, leading to large‐area, crack‐free, low‐roughness, flexible films after printing. This study demonstrates that all‐inorganic perovskite CsPbX3 nanosheets as a new class of 2D semiconductors have huge potential for flexible optoelectronic applications.