Biofouling is the adherence of micro-organisms on submerged surfaces, which is a common phenomenon presenting a serious hazard to industry and public health. Nanozymes with haloperoxidase mimic activity are promising options to combat biofouling because HBrO generated by them can kill micro-organisms effectively. However, in haloperoxidase mimic nanozyme-involved antibiofouling, massive H₂O₂ injection is a requisite, which causes secondary pollution. To achieve self-sufficient H₂O₂ supply in antibiofouling, a wheel-like polyoxometalate (POM) compound, Ni₁₆Mo₁₆P₂₄, was synthesized. As an artificial nanozyme, Ni₁₆Mo₁₆P₂₄ shows excellent haloperoxidase mimic activity. In the electrocatalytic oxygen reduction reaction (ORR), it shows typical two-electron character and H₂O₂ production rate reaches 1394.5, 1245.5 and 1053 mM g⁻¹ h⁻¹ at 0.1, 0.3 and 0.5 V (vs. RHE) in neutral electrolyte. With H₂O₂ produced by electrocatalysis, Ni₁₆Mo₁₆P₂₄ accelerates the conversion from Br⁻ to HBrO and achieves “additional H₂O₂ free” antibiofouling. For bifunctional Ni₁₆Mo₁₆P₂₄, the structure–activity connection is clarified for haloperoxidase mimic activity and electrocatalytic H₂O₂ production property. More importantly, an environmentally friendly antibiofouling strategy is developed.