Single-atom catalysts (SACs) hold great promise for maximized metal utilization, exceptional tunability of the catalytic site, and selectivity. Moreover, they can substantially contribute to lower the cost and abundancy challenges associated with raw materials. Significant breakthroughs have been achieved over the past decade, for instance, in terms of synthesis methods for SACs, their catalytic activity, and the mechanistic understanding of their functionality. Still, great challenges lie ahead in order to render them viable for application in important fields such as electrochemical energy conversion of renewable electrical energy. We have identified three particular development fields for advanced SACs that we consider crucial, namely, the scale-up of the synthesis, the understanding of their performance in real devices such as fuel cells and electrolyzers, and the understanding and mitigation of their degradation. In this Perspective, we review recent activities of the community and provide our outlook with respect to the aspects required to bring SACs toward application.