AbstractThe performance of perovskite cells closely relies on the quality of films, leading to a special focus on crystallization manipulation and defect control. In this study, a novel approach using 1D metal‐free perovskites, specifically DABCO‐NH4Cl3, is proposed to facilitate the crystallization process of 3D FAPbI3 perovskites, while simultaneously addressing surface defects. Analysis of crystallization kinetics reveals that the introduction of 1D metal‐free perovskites provides numerous nucleation sites, effectively slowing down crystal growth rates and resulting in the formation of uniform, large‐grain perovskite films. Furthermore, the organic groups present in 1D perovskites play a crucial role in passivating defects within the perovskite structure. The synergistic impact of these factors enables the perovskite to achieve an efficiency of 24.72% while demonstrating exceptional stability. This research offers a promising approach for controlling perovskite crystallization, leading to the development of high‐efficiency and stable perovskite materials.