This study introduces a novel electrochemical strategy for fabricating a robust and selective adsorptive interface by covalently grafting an azo-functionalized polymer (AZO Polymer) onto a copper electrode via diazonium chemistry for efficient Pb²⁺ removal from aqueous solutions. The synthesized poly(acrylamide-co-o-cresol) was characterized by FTIR, ¹H NMR, and XPS, confirming the successful incorporation of azo (–N=N–) and amide (–CONH₂) functionalities. Electrochemical grafting yielded a uniform, porous polymeric layer, as evidenced by SEM and N₂ physisorption, which increased the surface area and provided abundant coordination sites. The adsorption kinetics, monitored by electrochemical impedance spectroscopy (EIS) and quartz crystal microbalance (EQCM), revealed a rapid initial uptake, with Pb²⁺ removal efficiency reaching ~55% within 30 minutes and attaining a plateau of ~94% after 60 minutes (20 ppm, pH 7, 25°C). EIS analysis demonstrated a systematic increase in charge-transfer resistance (Rct) from ~820 Ω cm² to ~4650 Ω cm² over 60 minutes, correlating directly with Pb²⁺ accumulation. Remarkably, the electrode maintained >84% of its initial adsorption capacity after five consecutive adsorption–desorption cycles, demonstrating excellent reusability and interfacial stability. This work establishes electrochemically grafted AZO polymer layers as a durable, efficient, and regenerable platform for selective heavy metal remediation, merging covalent surface anchoring with tailored molecular affinity for sustainable water treatment.