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A sensitive, selective, and stable electrochemical sensor based on Mn1-xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) nanoparticle and Nafion-modified glassy carbon electrode (GCE) was designed and developed to detect Pb2+. The uniform and monodisperse Mn1-xZnxFe2O4 nanospheres were synthesized via a hard template-free (soft template) hydrothermal method. This research mainly focused on the influence of different Zn2+ substituting ratios inMn1-xZnxFe2O4 on sensing characteristics of the sensor. The highest response value to 0.6 µM Pb2+ was observed for the sensor using Mn0.4Zn0.6Fe2O4. In addition, the influence of experimental parameters (e.g., the kinds of electrolyte, pH, deposition potential, and time) on sensing performance was studied. When measured in 0.1MNaAc-HAc (pH = 2.0) at the deposition potential of -1.0V with the deposition time of 130 s, Mn1-xZnxFe2O4 and Nafionmodified GCE exhibited good sensitivity of 58.613 µA/µM, favorable repeatability, and an ultralow detection limit of 0.7 nM(based on S/N ratio = 3). The superior sensing properties to Pb2+ were attributed to the bigger electrochemically effective surface area with the addition of Zn2+, high adsorption capacity, and high specific surface area of Mn0.4Zn0.6Fe2O4 nanospheres. Using Nafion also enhanced the adsorption capacity and stability of the modified electrode. [ABSTRACT FROM AUTHOR]