Recent advances in agricultural biotechnology and sustainable farming have drawn attention to biochar as a multifunctional material for environmental remediation. Among its emerging applications, biochar has demonstrated remarkable potential in wastewater treatment, particularly as an efficient and sustainable adsorbent for pollutant removal. Numerous studies over the past decades have highlighted its effectiveness in eliminating a wide range of contaminants. This efficiency is mainly due to its abundant feedstock availability, simple production processes, and favorable surface and structural properties. This review summarizes current developments in biochar use for wastewater treatment, emphasizing its adsorption capabilities and the underlying mechanisms responsible for pollutant removal. Key modification strategies, physical, chemical, and biological, are discussed in detail to illustrate how biochar performance can be optimized for specific treatment goals. Furthermore, the prospects of biochar-based technologies are explored, with a focus on their role in addressing both inorganic and organic pollutants. This review also describes the use of biochar in adsorbing metals, organic contaminants, and industrial waste. The integration of biochar into sustainable water management systems presents a promising pathway toward achieving long-term environmental and agricultural resilience.