The synthesis and characterization of a novel zeolite-A/ZnO/graphene oxide (GO) nanocomposite were explored for the adsorption removal of heavy metals from pharmaceutical wastewater. The zeolite-A, ZnO nanoparticles, GO, and their composite were synthesized via hydrothermal, green, Hummer’s, and wet impregnation methods, respectively. The synthesized samples were characterized using some analytical tools. X-ray diffraction analysis confirmed the successful synthesis of zeolite A, ZnO, and GO, with characteristic peaks aligning with standard crystallographic data. The composite structure displayed unique diffraction shifts, indicating the interaction between ZnO and the zeolitic framework. Scanning electron microscopy revealed distinct morphological features of individual components and their successful integration within the composite. Energy dispersive X-ray spectroscopy and elemental mapping further validated the composition of the nanocomposite and homogeneity. Brunauer–Emmett–Teller analysis demonstrated a high surface area of 115.70 m²/g for the composite, significantly higher than its individual constituents, alongside improved pore structure and volume. The adsorption performance was assessed for Cd, Fe, and Cr ions, showing superior removal efficiencies within 40–50 min, with maximum adsorption capacities of 107.92 mg/g (Cr), 98.28 mg/g (Fe), and 94.51 mg/g (Cd). Increased nanosorbent dosage and temperature positively influenced removal efficiency, achieving complete elimination at optimized conditions. Adsorption kinetics followed a pseudo-second-order model, confirming chemisorption as the dominant mechanism, while equilibrium data aligned with the Langmuir isotherm, indicating monolayer adsorption. The composite exhibited excellent stability and reusability across multiple cycles, demonstrating its potential for practical wastewater treatment applications and its sustainability for heavy metal remediation, offering a promising solution for mitigating environmental pollution from pharmaceutical wastewater.