A novel poly(crystal violet)/graphene-modified glassy carbon electrode (PCV/Gr/GCE) was fabricated for the simultaneous determination of Pb2+ and Cd2+. The electrochemical behavior of both species at the PCV/Gr/GCE was investigated employing cyclic voltammetry. In acetate buffer, the modified electrode showed an excellent electrocatalytical effect on the oxidation of both species and was further used for their determination. Under optimized analytical conditions, the oxidation peak currents of Pb2+ and Cd2+ obtained by differential pulse voltammetry in pH 4.6 acetate buffer showed a linear relationship with their concentrations in the ranges of 2.00 × 10−8–1.95 × 10−5 mol L−1 and 4.00 × 10−8–5.58 × 10−5 mol L−1, respectively. The developed method has excellent sensitivity, selectivity, reproducibility and has been successfully applied to the determination of Pb2+ and Cd2+ in water samples.