Environmental sustainability represents a major challenge facing our world. Recent advances in synthetic micro/nanomachines have opened new horizons for addressing environmental problems. This review article highlights the opportunities and challenges in translating the remarkable progresses in nanomotor technology toward practical environmental applications. It covers various environmental areas that would benefit from these developments, including nanomachine-enabled degradation and removal of major contaminants or nanomotor-based water quality monitoring. Future operations of autonomous intelligent multifunctional nanomachines, monitoring and responding to hazardous chemicals (in a "sense and destroy" mode) and using bioinspired chemotactic search strategies to trace chemical plumes to their source, are discussed, along with the challenges of moving these exciting research efforts to larger-scale pilot studies and eventually to field applications. With continuous innovations, we expect that man-made nano/microscale motors will have profound impact upon the environment.