The rising levels of heavy metal pollution in water bodies present major environmental and public health issues. Conventional methods for remediation often come with high costs and produce secondary waste, which can pose additional environmental risks. As an alternative, chitosan—a natural, biopolymer derived from chitin—has gained attention as a promising biosorbent for heavy metal removal. Its advantages include biocompatibility, biodegradability, and a strong ability to bind metal ions effectively. This review explores chitosan’s capacity to adsorb various heavy metals and examines its practical applications in biosorption technology. Key factors that impact its adsorption efficiency, such as solution pH, metal concentration, and contact time, are discussed. Additionally, structural modifications to enhance chitosan’s performance, including cross-linking and nanoparticle incorporation, are analyzed to highlight improvements in adsorption efficiency. By assessing these elements, this review aims to offer a comprehensive perspective on the role of chitosan in environmental management, particularly for treating heavy metal contamination in wastewater. The findings underscore chitosan's potential as a sustainable solution in pollution control, emphasizing its advantages over traditional methods and its capacity to contribute to cleaner water resources.