The synthesis and adsorption applications of polymethyl methacrylate (PPMA)- and zinc oxide nanoparticles (ZnO NPs)-based adsorbent (PMMA/ZnO) were investigated in this work. FESEM, EDX, FTIR and P-XRD techniques were used to characterise the PMMA/ZnO nanocomposite-based adsorbent. PMMA/ZnO was utilised in the adsorption-based removal of toxic Pb2+, Cd2+and Cr6+ions from aqueous solutions. PMMA/ZnO was highly capable of removing Pb2+, Cd2+and Cr6+ions at optimised conditions such as 60 min of agitation, 1 g of PMMA/ZnO, pH of 6 and temperature of 60 °C, respectively. Under laboratory conditions, different isotherm and kinetic models were used to evaluate the appropriateness of the adsorption process. The suitability order of isotherm models was Freundlich > Langmuir > Elovich, with rate constants of 5.216, 12.0336 and 4.926 g mg−1min−1for Pb2+, Cd2+and Cr6+ions, respectively, evaluated using the pseudo-second-order model.