With the development of human society, the consumption of fossil fuels is rapidly increasing. However, renewable energy sources could cause future energy shortages and further damage our environment. Therefore, pursuing renewable energy sources and more importantly using suitable energy conversions techniques are in an emergency need. Catalyst is one of the most important components of these devices. Thus, developing highly efficient and low-cost single-atom catalysts (SACs) for electrochemical reactions is crucial. However, because of the highly unsaturated coordination environment, the stability of SACs can be a challenge for practical applications. In this chapter, we summarize the strategies to synthesize stable SACs and then highlight some of their applications in electrochemical energy applications. Finally, we offer a perspective on the development of advanced SACs for future research.