Organic–inorganic hybrid perovskites (OIHPs) have been explosively investigated mainly due to their potential applications in optoelectronics. Despite the electronic charge transport, phenomena regarding the spin‐polarized electronic transport in OIHPs‐based spintronic devices and the role of ferromagnet/OIHP spinterfaces remain unclear. In this work, the spin injection, accumulation, transport, and detection at room temperature for a vertical perovskite spin valve (PeSV) consisting of Ni/CH₃NH₃PbI_3−xCl_x/Ni is reported. An in‐plane anisotropic magnetoresistance (AMR) and a PeSV related magnetoresistance (MR) show remarkable magnetic switching behaviors due to the formation of Ni/CH₃NH₃PbI_3−xCl_x spinterfaces, and the ferromagnetic coupling between two spin quantization axes of the spinterfaces. With assists of capacitance–frequency (C − − f) measurements under magnetic fields, the spin accumulation that occurs at the Ni/CH₃NH₃PbI_3−xCl_x interface can be detected at the spin parallel (↑↑) and antiparallel (↑↓) configurations. Owing to a strong orbital interaction at the Ni/CH₃NH₃PbI_3−xCl_x hybrid interface, the spin‐sensitive electron paramagnetic spectroscopy (EPR) reveals significant change of the magnetic moment (µ). It is believed that the solution processed CH₃NH₃PbI_3−xCl_x and the formation of the Ni/CH₃NH₃PbI_3−xCl_x spinterface may hold an exceptionally important role for future hybrid optospintronic applications.