Landfill leachate comprises highly toxic and hazardous compounds posing adverse health effects to the ecosystem and human populations. These leachates must be subjected to suitable treatment before discharging to the environment. However, the higher operational cost and presence of recalcitrant matter in the leachate make the conventional physico-chemical processes incompetent for treatment. Recent advancements in biological processes over physico-chemical processes result in the development of aerobic granular reactor (AGR) for treating landfill leachate. Small footprint, less energy demand, high microbial activity, long-term operational stability with better removal of organic pollutants, and resistance to high shock load make AGR a promising technique for treating leachate. Longer granulation time and instability of aerobic granules are some of the major shortcomings that limit its commercial application. Additionally, the single-stage treatment of landfill leachate using AGR poses several difficulties, such as low organic and recalcitrant pollutant removal efficiency, which needs post-treatment. Hence, an integrative approach is imperative for treating landfill leachate with a high organic load to meet the effluent standard. The present study highlights an in-depth critical review of various biological processes, recent developments in AGR, and the factors affecting its performance, mass balance, and the kinetics involved during landfill leachate treatment. Subsequently, the integrated process for the treatment of landfill leachate has been summarized along with the future prospects of AGR.