Quasi‐two‐dimensional (Q‐2D) Dion‐Jacobson (DJ) organic‐inorganic hybrid perovskites based on CsPbBr3 are promising candidates for photodetection. Previous studies have predicted that the photoresponse of such materials with high inorganic‐layer numbers (n) will be more protruding in this portfolio. However, until now, only bilayered (n=2) CsPbBr3‐based DJ‐type hybrid perovskites are obtained and the higher number of layers (n>2) remain completely unexplored, owing to the relatively high formation energies. Here, by incorporating diamine into the 3D CsPbBr3 motif, a new Q‐2D trilayered CsPbBr3‐based DJ‐type hybrid perovskite that contains organic cation and inorganic Cs metal, namely (4‐AMP)Cs2Pb3Br10 (1, 4‐AMP2+=4‐(aminomethyl)piperidinium, n=3), is obtained. Excitingly, 1 exhibits excellent photoresponse, superior to its single‐layered and bilayered counterparts. The resulting photodetectors thus exhibit a large on/off ratio (>103), high photodetectivity (6.5×1010 Jones) and fast response speed (193 μs). As far as we know, 1 is the first Q‐2D CsPbBr3‐based DJ‐type hybrid perovskites with high n numbers. Our results may widen the range of the potential material in application of photodetection and will be helpful to design hybrid perovskites for other advanced optoelectronic devices. Photodetectors: By incorporating diamine into the 3D CsPbBr3 motif, the first quasi‐2D trilayered CsPbBr3‐based Dion‐Jacobson hybrid perovskite (4‐AMP)Cs2Pb3Br10 (1, where 4‐AMP2+=4‐(aminomethyl)piperidinium), is acquired. Photodetectors based on 1 exhibit excellent photoresponse, superior to its monolayered and bilayered counterparts. Our results may widen the range of the potential material of photodetection and will be helpful to design hybrid perovskites for other advanced optoelectronic devices.