The multifunctional two‐dimensional (2D) organic‐inorganic hybrid perovskites have potential applications in many fields, such as, semiconductor, energy storage and fluorescent device etc. Here, a 2D Ruddlesden‐Popper (RP) perovskite (IPA)2(FA)Pb2I7 (1, IPA+=C3H9NI+, FA+=CN2H5+) is determined for its photophysical properties. Strikingly, 1 reveals a solid reversible phase transition with Tc of 382 K accompanied by giant entropy change of 40 J mol−1 K−1. Further optical investigations indicate that 1 reveals a narrow direct bandgap (2.024 eV) attributed to the slight bending of I−Pb‐I edge and inorganic [Pb2I7]n layer and a superior photoluminescence (PL) emission with super long lifetime of 0.1607 ms. It is believed that this work will pave an avenue to further design multifunctional semiconductors that combines energy storage and photoelectric materials. [ABSTRACT FROM AUTHOR]