Hydrothermal carbonisation (HTC) technology benefits the environment by lowering greenhouse gas emissions and promoting sustainable waste management practices while supporting circular economy principles. Over the past two years, research has focused on optimising HTC process parameters, broadening the range of suitable feedstocks, and enhancing the properties of hydrochar and byproducts. This review discusses the characteristics of the hydrochar, including its calorific value, surface area, and nutrient content, and the influence of these parameters by feedstock type in the HTC. Furthermore, it reviews the suitability of hydrochar derived from different feedstocks in applications such as renewable solid fuel, soil amendment and environmental remediation. By analysing the most recent research advancements and identifying the associated challenges, this review underscores the importance of HTC in promoting sustainable waste management practices and enhancing resource utilisation in a circular economy framework.