The increasing energy consumption and environmental concerns have driven the development of costeffective, high-efficiency clean energy. Advanced functional nanomaterials and relevant nanotechnologies are playing a crucial role and showing promise in resolving some energy issues. In this view, we focus on recent advances of functional nanomaterials in clean energy applications, including solar energy conversion, water splitting, photodegradation, electrochemical energy conversion and storage, and thermoelectric conversion, which have attracted considerable interests in the regime of clean energy. Abstract The increasing energy consumption and environmental concerns have driven the development of costeffective, high-efficiency clean energy. Advanced functional nanomaterials and relevant nanotechnologies are playing a crucial role and showing promise in resolving some energy issues. In this view, we focus on recent advances of functional nanomaterials in clean energy applications, including solar energy conversion, water splitting, photodegradation, electrochemical energy conversion and storage, and thermoelectric conversion, which have attracted considerable interests in the regime of clean energy.