In this paper, we present a facile approach to enhance the effciency and stability of perovskite solar cells (PSCs) by incorporat-ing perovskite with microporous indium-based metal–organic frame-work [In12O(OH)16(H2O)5(btc)6]n (In-BTC) nanocrystals and forming heterojunction light-harvesting layer. The interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystalliza-tion of perovskite inside the regular cavities, endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/defects. Consequently, the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion effciency (PCE) of 20.87％, sur-passing the pristine device (0.76 and 19.52％, respectively). More impor-tantly, over 80％ of the original PCE is retained after 12 days of exposure to ambient environment (25 °C and relative humidity of ～ 65％) without encapsulation, while only about 35％ is left to the pristine device.