<p>Efficient management of sewage sludge (SS), a byproduct of wastewater treatment, remains a critical environmental challenge. This paper emphasizes recent research on the synthesis and applications of SS-derived biochar. The control parameters of the thermochemical route such as pyrolysis, gasification, torrefaction, and hydrothermal carbonization used to transform SS into biochar impact its structure, chemistry, and catalytic properties. The characteristics of SS biochar, such as specific surface area, porosity, and surface activity, depend on the content of the sludge and the thermochemical process control parameters. Physical properties of the SS greatly vary depending upon the source and type of SS used. As a result, several functional biochar with energy storage, adsorption, and catalytic functions could be created by varying the residence time, temperature, heating rate, and gas environment. The desired properties of biochar also depend on volatile matter, carbon, and ash content in the SS. At the same time, the stability of biochar is influenced by the adsorption process, pore structure, minerals, surface area, pH, and particle size. SS biochar, characterized by its high porosity, extensive surface area, and significant polarity, excels in adsorbing a wide range of pollutants, including antibiotics and heavy metals. The environmental applications of SS biochar for water and soil remediation have also been presented and discussed. Biochar technology appears to be a cost-effective and environmentally sustainable approach to treating pollution.</p>