Chiral quasi‐2D perovskite single crystals (SCs) were investigated for their circular polarized light (CPL) detecting capability. Quasi‐2D chiral perovskites, (R)‐β‐MPA2MAPb2I7 ((R)‐β‐MPA=(R)‐(+)‐β‐methylphenethylamine, MA=methylammonium), have intrinsic chirality and the capability to distinguish different polarization states of CPL photons. Corresponding quasi‐2D SCs CPL photodetector exhibit excellent detection performance. In particular, our device responsivity is almost one order of magnitude higher than the reported 2D perovskite CPL detectors to date. The crystallization dynamics of the film were modulated to facilitate its carrier transport. Parallel oriented perovskite films with a homogeneous energy landscape is crucial to maximize the carrier collection efficiency. The photodetector also exhibits superior mechanical flexibility and durability, representing a promising candidate for sensitive and robust CPL photodetectors. Chiral quasi‐2D perovskites possess intrinsic chirality and thus exhibit circular polarized light (CPL) detection capability. A flexible chiral quasi‐2D perovskite thin‐film photodetector, which exhibits excellent CPL detection efficiency and durability, is presented that is a promising candidate for sensitive and robust CPL photodetectors.