AbstractEnhancing device lifetime is one of the essential challenges in perovskite solar cells. The ultrathin Eu‐MOF layer is introduced at the interface between the electron‐transport layer and the perovskite absorber to improve the device stability. Both Eu ions and organic ligands in the MOF can reduce the defect concentration and improve carrier transport. Moreover, due to the Förster resonance energy transfer effect, Eu‐MOF in perovskite films can improve light utilization and reduce the decomposition under ultraviolet light. Meanwhile, Eu‐MOF also turns tensile strain to compressive strain in the perovskite films. As a result, the corresponding devices achieve a champion power conversion efficiency (PCE) of 22.16%. In addition, the devices retain 96% of their original PCE after 2000 h under the relative humidity of 30% and 91% of their original PCE after 1200 h after continuous 85 °C aging condition in N₂.