Recently, carbazole-based organic cations have garnered interest for their potential application in two-dimensional (2D) layered hybrid perovskite solar cells because of their strong hole extraction and transport as well as humidity resistance. However, the potential incorporation of carbazole-based Ruddlesden–Popper 2D hybrid perovskites in photodetectors has been largely unexplored. In this study, we synthesized ammonium 1-(9H-carbazol-9-yl) ethanaminium iodide (CzEAI) and fabricated (CzEA)2PbI4 2D perovskite thin films via varying solvent conditions to control film morphology. We constructed photodiode-type photodetectors with the active layer of (CzEA)2PbI4 2D perovskites and demonstrated a specific detectivity of 6.95 × 1010 Jones at 485 nm illumination without external bias. These results demonstrate the potential of carbazole-based 2D perovskites in a wide range of optoelectronic applications.