As one of the main forms and intermediate carriers of energy, it is impressive to expand the application scope of heat energy, thereby boosting innovations in heat harvesting, conversion, storage, regulation, and utilization associated with the relevant techniques. Phase change materials (PCMs), as a state-of-the-art latent heat storage technique, have garnered increasing interest in heat-related applications over the past decades, and abundant high-performance PCMs with excellent shape stability and salient thermal conductivity have been developed. This review focuses on the issues concerning organic PCMs from the perspectives of flexible, multifunctional, and smart phase change composites, along with emerging applications and processing technologies, which are expected to offer possible guidance for the exploration of next-generation advanced functional phase change composites.