As an important reactive oxygen species (ROS) with selective oxidation, singlet oxygen (<sup>1</sup>O<sub>2</sub>) has wide application prospects in biology and the environment. However, the mechanism of <sup>1</sup>O<sub>2</sub> formation, especially the conversion of superoxide radicals (·O<sub>2</sub><sup>-</sup>) to <sup>1</sup>O<sub>2</sub>, has been a great controversy. This process is often disturbed by hydroxyl radicals (·OH). Here, we develop a molybdenum cocatalytic Fenton system, which can realize the transformation from ·O<sub>2</sub><sup>-</sup> to <sup>1</sup>O<sub>2</sub> on the premise of minimizing ·OH. The Mo<sup>0</sup> exposed on the surface of molybdenum powder can significantly improve the Fe<sup>3+</sup>/Fe<sup>2+</sup> cycling efficiency and weaken the production of ·OH, leading to the generation of ·O<sub>2</sub><sup>-</sup>. Meanwhile, the exposed Mo<sup>6+</sup> can realize the transformation of ·O<sub>2</sub><sup>-</sup> to <sup>1</sup>O<sub>2</sub>. The molybdenum cocatalytic effect makes the conventional Fenton reaction have high oxidation activity for the remediation of organic pollutants and prompts the inactivation of <i>Staphylococcus aureus</i>, as well as the adsorption and reduction of heavy metal ions (Cu<sup>2+</sup>, Ni<sup>2+</sup>, and Cr<sup>6+</sup>). Compared with iron powder, molybdenum powder is more likely to promote the conversion from Fe<sup>3+</sup> to Fe<sup>2+</sup> during the Fenton reaction, resulting in a higher Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio and better activity regarding the remediation of organics. Our findings clarify the transformation mechanism from ·O<sub>2</sub><sup>-</sup> to <sup>1</sup>O<sub>2</sub> during the Fenton-like reaction and provide a promising REDOX Fenton-like system for water treatment.