Zinc-rich coatings provide cathodic protection for metal substrates through the sacrificial anode action of zinc powder, which is widely used in marine equipment. However, zinc powder is easily covered by nonconductive corrosion products during service, resulting in low actual utilization rate of zinc powder and the failure of cathodic protection, which seriously restricts the long-term protective life of the coating. In this study, we designed a zinc-rich epoxy coating modified with 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), successfully builting an intelligent coating with a multilevel protection mechanism. The experimental results show that adding 2 wt·% HEDP (70Zn-HEDP) to a coating with a zinc powder content of 70 wt·% can increase the duration of its cathodic protection to twice that of the unmodified coating with a zinc powder content of 70 wt·% (70Zn), improve the utilization rate of zinc powder in the coating, and significantly slow down the zinc corrosion products, generate and enhance the physical blocking performance of the coating. With integrated electrochemical testing, morphological characterization, and DFT theoretical simulation, we reveal the multilevel protection mechanism of HEDP's multifunctionality: it preferentially chelates Zn2+ to sustain zinc reactivity and prolong cathodic protection, deposits insoluble complexes to seal coating defects. It ultimately generates a protective Zn/Fe-HEDP passivation layer upon exposure to steel. The multifunctional protection mechanism of organophosphates provides ideas for the design of the next generation of zinc-based anticorrosion coatings with both intelligent response and long service life.