Perovskite solar cells (PSCs) face critical challenges owing to their intrinsic instability under harsh environmental conditions. Although various strategies are explored to enhance stability, their effects remain temporary. Herein, dendrimers are designed that serve as volatile reservoirs, enabling repeated self-healing while simultaneously enhancing power conversion efficiency (PCE). PSCs containing these dendrimers achieve a PCE exceeding 26% and recover 90% of their initial PCE after ten cycles of alternating high-humidity and dry conditions. Then the self-healing mechanism is elucidated, which is facilitated by the dendrimers capturing volatile FA and interacting with PbI6 octahedra to form intermediate phases. These phenomena afford a reversible transition between perovskite and degraded perovskite phases. This approach offers a sustainable pathway toward semi-permanent PSCs by enabling continuous self-healing of perovskite materials.