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Study of Pb desorption processes from clay minerals by chelating ligands is crucial to better understand the fate and transport of Pb in soil and sediment environments. In this study, Pb desorption from a Pb-loaded montmorillonite (MMT) was studied as affected by ethylenediaminetetraacetic acid (EDTA) and its two alternative eco-friendly chelating agents, i.e., methylglycine diacetic acid (MGDA) and glutamic-N,N-diacetic acid (GLDA) at two concentrations of 0.25 and 1.0 mM. The impacts of a 30-day residence time on the rate and quantity of Pb desorption were also evaluated. The result showed that Pb desorption kinetics was biphasic with an initial rapid phase, lasting for about 3 h, followed by a slow phase, lasting to 12 h. The degree of Pb desorption from Ca-MMT was proven to be governed by the nature and concentration of the chelating ligands presented in the systems. The capacity of the ligands to desorb Pb from Ca-MMT was in the order EDTA > > MGDA > GLDA, according to the decreasing order in the stability constants of their complexes with Pb ions. The aging of the MMT systems caused a significant reduction in both Pb desorption quantity and rate parameters. The results suggest that EDTA would have a more serious Pb-mobilizing impact than GLDA and MGDA in contaminated soil and sediments which contain Ca-MMT as a major clay constituent.