Biosorption of zinc by living biomasses of metal resistant symbiotic bacterium Mesorhizobium amorphae CCNWGS0123 was investigated under optimal conditions at pH 5.0, initial metal concentrations of 100mgL(-1), and a dose of 1.0gL(-1). M. amorphae exhibited an efficient removal of Zn2+ from aqueous solution with maximum biosorption capacity of 120.85mgg(-1). Moreover, more than 70% Zn2+ could be recovered from Zn-loaded biomass at pH 1.0. Both the Langmuir and Freundlich isotherms provided a better fit to experimental data for Zn2+ sorption with correlation coefficients of 0.9885. Kinetics models suggested there was more than one step involved in the Zn2+ sorption process, while a pseudo-second-order model was more suitable to describe the kinetic behavior accurately, indicating a chemisorption process. Carbonyl, amino, carboxyl, and aromatic groups were responsible for the biosorption of Zn2+ by M. amorphae. Cellular deformation, precipitate, and damage were found after Zn2+ treatment. Competitive sorption revealed Cu2+, Cd2+, and Ni2+ were competed with Zn2+ for adsorption sites with the order: Cu2+>Cd2+>>Ni2+.