Single-atom catalyst as an advanced co-catalyst shows promising potential in energy fields such as water splitting, degradation of pollutants, chemical conversion field, etc. It takes advantage of increased active sites and sub-nanometer size effects with electron confinement by reducing the size of supported noble metals; furthermore, a single-atom catalyst maximizes the atomic efficiency of metals and provides a low atomic coordination number for the active center. In this work, we discovered that the isolated single atoms (SAs) stabilized by the support of g-C₃N₄ as named by SA-Pt/g-C₃N_4. Single-atom catalyst is synthesized by anchoring Pt atoms in graphitic carbon nitride (g-C₃N₄) with different Pt-loading [0.01wt% to 1wt% H₂PtCl₆·(H₂O)₆]. Under flexocatalytic process, the k rate constant of the SA-Pt/g-C₃N₄ with 0.01wt% of Pt is 3×10^-3 s^-1 for decomposition of dye molecules, which is 2 times the pristine g-C₃N₄. In addition, the flexocatalytic hydrogen evolution of SA-Pt/g-C₃N₄ provides H₂ production, reaching nearly 125 μmolgh^-1, which is 312% of the pristine g-C₃N₄ (~40 μmolgh^-1). The working mechanism of flexocatalytic activity suggests the mechanical strain-induced flexoelectric potential (flexopotential) and proceeding with redox's electrochemical reaction. In addition, the single-atom act as a critical role in attracting electrons to accelerate the reaction process. The single-atom catalyst of 2D materials is highly potential for applying in water splitting and degradation of pollutants through the flexocatalytic process.