<p>The catalytic potential of biochar, a new carbonaceous material with robust adsorption capabilities, is being recognized by environmental applications more and more. This thorough analysis explores the core ideas behind the processes that produce persistent free radicals (PFRs) during biomass pyrolysis as well as the different detection techniques used to find PFRs. A thorough analysis shows how certain pyrolysis parameters, such as temperature (between 300 and 600 °C) and heating rate (between 5 and 50 °C/min), in addition to the degradation of lignin (which makes up 15–35% of biomass) and other biomass components, affect the synthesis of PFR in biochar. The article provides a thorough examination of many PFR detection techniques, such as electron paramagnetic resonance (EPR) spectroscopy, which has shown 70% detection effectiveness. Furthermore, it investigates the biochar-PFRs’ catalytic potential in environmental remediation, emphasizing how well they work in redox systems, sophisticated oxidation processes, and photocatalytic applications. With research demonstrating up to 80% degradation of pollutants and a 90% decrease of metal ions, the review highlights the usefulness of biochar-PFRs in pollution management and water treatment. The assessment also discusses important future directions and difficulties, highlighting the need for ongoing developments to fully use PFRs for environmentally friendly solutions. Understanding the redox behavior of metal ions in biochar-PFR systems and scaling up applications for wider effects are two of the main issues that have been highlighted.</p> Graphical Abstract <p></p>