Atomically dispersed catalysts have received extensive research attention, because they exhibit excellent activity and unique selectivity for many important catalytic reactions. The atomically dispersed nature of these metal catalysts confers their unique electronic structures as well as designated coordination-unsaturated environments for the optimized adsorption/activation of the reactants. One grand challenge faced by these atomically dispersed catalysts is that the supported isolated metalatoms are usually thermally unstable and tend to aggregate into large clusters/particles at evaluated reaction temperatures. As a result, most reported atomically dispersed catalysts have an extremely low metal loading below 1.5 wt%. Because of the extremely low metal loading, many atomically dispersed catalysts suffer from low mass-specific activity, which is often considered more crucial, especially in industrial applications. Therefore, developing new strategies for constructing atomically dispersed catalysts with high metal loading, high thermal stability, and high catalytic performance is of great importance.