Single-atom catalysts (SACs) offer uniform active sites and exhibit extremely high selectivity towards desired products by ensuring consistent reaction pathways and minimizing the generation of undesired byproducts. Metal atoms interact with their support materials to determine the catalytic activity of SACs. Stronger coordination can enhance stability by preventing aggregation and ensuring the longevity of the isolated active site. The systematic design of next-generation catalysts necessitates a profound understanding and meticulous control of the metal-support synergy within SACs. The strategic integration of dual-atom site catalysts (DACs) and single-atom alloy catalysts has emerged as viable and efficient pathway to optimize catalytic performance. DACs possess flexible active sites that work , resulting in improved catalytic activity, selectivity, and stability. SAAs offer well-defined active sites and enhanced catalytic performance due to the high concentration of single-atom sites and bimetallic synergy. In particular, the neighboring metal single atoms exhibit metal−metal interactions, and the intersite distances of these neighboring atomic sites significantly impact electrocatalytic performance. This comprehensive review meticulously discusses the latest breakthroughs in SACs designed for electrochemical water splitting. We delve into the distinctive structural and electronic attributes of single-site, dual-site, and alloy SAC configurations, elucidating how these features enhance the water splitting reaction rates.