Single‐atom catalysts (SACs) have emerged to be a new research frontier in catalysis due to their distinctive physical and chemical properties, including better catalytic performance, stability, and recyclability. However, the widely used organic synthesis methods for SACs limit the ability to uniformly distribute single atoms’ water‐soluble precursors on the support of the catalysts. A water‐based synthesis of single gold (Au) atom catalyst is used in this work. Through this method, water‐soluble Au precursors are successfully turned into Au single atoms embedded in metal–organic framework‐derived nitrogen‐containing nanoporous carbon. The resulting catalyst is applied on the reduction of 4‐nitropenol. The catalytic performance of the reaction reaches 100% conversion in 30 min, while utilizing Au nanoparticles as active sites on the same support can only get 70% conversion under the same reaction conditions.