Two-dimensional (2D) perovskites are hybrid layered materials in which the inorganic lattice of an octahedron is sandwiched by organic layers. They behave as a quantum-well structure exhibiting large exciton binding energy and high emission efficiency, which is excellent for photonic applications. Hence, the cavity modulation and cavity devices of 2D perovskites are widely investigated. In this review, we summarize the rich photophysics, synthetic methods of different cavity structures, and the cavity-based applications of 2D perovskites. We highlight the strong exciton–photon coupling and photonic lasing obtained in different cavity structures. In addition, functional optoelectronic devices using cavity structures of 2D perovskites are also reviewed.