Perovskite solar cells (PSCs) are next-generation solar cells; they are replacing silicon-based solar cells due to their higher efficiency, greater cost-effectiveness, and enhanced potential for various applications. Exceeding the efficiency of crystalline silicon-based solar cells, the commercialization of PSCs has driven not only the development of perovskite photoactive materials but also charge transport layer advancements, interfacial engineering, and processing technologies. PSCs were developed later than dye-sensitized solar cells and organic solar cells; the adoption of techniques previously employed in these technologies is significant to enhancing their performance. Among them, polymers are widely employed in perovskite solar cells to facilitate efficient charge transport, provide interfacial passivation, enhance mechanical flexibility, enable solution-based processing, and improve environmental stability. In this review, we highlight the roles of polymer materials as charge transport layers, interfacial layers, and other functional layers for highly efficient and stable PSCs.