Imidazolium‐based ionic liquids have been established as promising candidates for additives in perovskite solar cells. Herein, 1‐(1‐ethyl‐3‐imidazolium)propane‐3‐sulfonate (EIMS) zwitterionic ionic liquid is studied as additive to enhance the performance of the FAPbI₃ perovskite solar cells. The addition of EIMS leads to the generation of porous PbI₂ film, which promotes the reaction of PbI₂ with FAI solution and thus improves the quality of FAPbI₃ perovskite film during the two‐step sequential spin coating. It is revealed that EIMS accelerates the extraction of electron, inhibits the formation of pinhole, and reduces the defect density, which leads to an increased efficiency of 22.1%. The hysteresis index is also reduced from 0.142 to 0.009, which indicates the addition of EIMS can realize a negligible hysteresis behavior in the solar cells. Moreover, devices prepared with EIMS retain above 96% of the original power conversion efficiency (PCE) value after being stored in dry air for 45 days. All these results demonstrate that the imidazolium‐based zwitterionic ionic liquid additive strategy is a promising way for high‐performance perovskite solar cells.