Recognized for their superior optoelectronic features and multifunctionality, metal halide perovskite solar cells (PSCs) have become a subject of considerable scientific attention. Although laboratory-scale PSCs have advanced rapidly, the PCE of large-area perovskite solar modules (PSMs) remains lower, mainly owing to the poor quality of large-area perovskite films. Compared to small-area PSCs fabricated via spin coating under an inert atmosphere, the complex air environment and the increasing uncontrollable factors of large-area coating technology pose significant challenges for achieving high-quality perovskite films, leading to high efficiency loss from cell to module. In this work, we report a multifunctional additive Mercaptoacetamide (MAA) to regulate the growth of perovskite while passivating defects to achieve efficient and stable PSCs. The multiple interactions between MAA and various components of perovskite precursor delay the crystallization rate and extend the processing window of perovskite. This approach addresses the issue of uneven crystallization caused by the complex crystallization kinetics during large-area coating process, resulting in larger grain size and better crystal orientation. The reduction in vacancy defects, coupled with the strong reductive effect of MAA, effectively suppresses the hydrolysis and oxidation of perovskite films in air, facilitating the fabrication of high-quality large-area perovskite films. This approach enabled small-area PSCs to reach an outstanding champion PCE of 25.52%. Leveraging this effective methodology, we further scaled up the device area, attaining champion efficiencies of 22.87% and 20.18% for perovskite mini-modules with aperture areas of 11.09 cm2 and 113 cm2, respectively. Besides, the encapsulated devices exhibit excellent photothermal and damp-heat stability.