The efficiency and stability of perovskite solar cells (PSCs) can be greatly affected by various factors such as passivating the perovskite film, oxidizing the hole-transport material of 2,2′,7,7′-tetras(N,N-p-methoxyaniline)-9,9′-spirodifluorene (Spiro-OMeTAD), and inhibiting the iodide migration. Here we introduce a multifunctional starch-iodine complex in the perovskite film to enhance the fill factor and stability of PSCs. Results demonstrate that the starch-iodine complex from the perovskite film can release iodine molecules to gently oxidize the Spiro-OMeTAD, which can significantly increase the PSC's fill factor. Moreover, the remaining starch can effectively passivate the perovskite film to obviously improve the PSC's long-term stability. Furthermore, the starch-iodine complex can absorb and store the iodide ions to generate a starch-triiodide complex, which can release iodide ions to promote iodide defect self-healing and suppress iodide migration in the perovskite films, resulting in a further enhancement of the PSC's long-term stability. As a result, the PSC based on the starch-iodine complex obtains a superior cell efficiency of 22.60% with a high fill factor of 79.54%, and keeps 91.12% of its original efficiency after 1500 h.