In this study, a screen-printed electrode (SPE) was modified with gold nanoparticles (AuNPs) and an ionophore (AuNPs/ionophore/SPE) to provide an electrochemical sensor for the sensitive and selective determination of lead ions using linear sweep anoding stripping voltammetry (LSASV). The effect of electrochemical parameters, including supporting electrolyte, pH, deposition potential, deposition time, and scan rate, on the sensitivity of the sensor for the detection of Pb2+ was investigated. Under optimized conditions [deposition time 240 s, deposition potential −1.2 V, Tris-HCl (0.1 mol L−1, pH 2), and scan rate of 0.1 Vs−1], the linear sweep voltammogram at −0.5 V was related to the concentration of Pb2+ in the range of 0.4 to 20 μg mL−1 Pb2+ with a limit of detection (LOD) of 0.082 μg mL−1. The method was used to determine Pb2+ ions in river and tap water with satisfactory results. The modified electrode displayed benefits such as high sensitivity and selectivity, long time stability, easy preparation, and wide linear range.