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-xZnxFe₂O₄nanospheres were synthesized via a hard template-free (soft template) hydrothermal method. This research mainly focused on the influence of different Zn²⁺substituting ratios in Mn1-xZnxFe₂O₄on sensing characteristics of the sensor. The highest response value to 0.6 mu M Pb²⁺was observed for the sensor using Mn_0.4Zn_0.6Fe₂O₄. 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 0.1 M NaAc-HAc (pH = 2.0) at the deposition potential of -1.0V with the deposition time of 130 s, Mn1-xZnxFe₂O₄and Nafion-modified GCE exhibited good sensitivity of 58.613 mu A/mu M, 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 Mn_0.4Zn_0.6Fe₂O₄nanospheres. Using Nafion also enhanced the adsorption capacity and stability of the modified electrode.