Approximately half of the global primary energy consumption is wasted in the form of low-grade (i.e., low-temperature) thermal energy, which has been traditionally overlooked and rejected to the environment, leading to low overall energy utiliization efficiencies. In recent years, there has been a growing urgency for deep decarbonization and energy security, as well as a change to global economic conditions, which have sparked an increased interest in the utilization of low-grade thermal energy. Research has increasingly focused on a diverse range of technologies and applications for harnessing this energy resource. The Special Issue ‘Low-grade thermal energy utilization: technologies and applications’ served as a platform for presenting state-of-the-art research on the management and utilization of low-grade thermal energy. This editorial article reviews the articles featured in the Special Issue, and provides commentary on these contributions.