Removal of lead (II) from aqueous solutions was studied by using pretreated fish bones as natural, cost‐effective, waste sorbents. The effect of pH, contact time, temperature, and metal concentration on the adsorption capacities of the adsorbent was investigated. The maximum adsorption capacity for Pb (II) was found to be 323 mg/g at optimum conditions. The experiments showed that when pH increased, an increase in the adsorbed amount of metal of the fish bones was observed. The kinetic results of adsorption obeyed a pseudo second‐order model. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data of Pb (II) adsorption and the value of R_L for Pb (II) was found to be 0.906. The thermodynamic parameters related to the adsorption process such as E_a, ΔG°, ΔH°, and ΔS° were calculated and E_a, ΔH°, and ΔS° were found to be 7.06, 46.01 kJ mol⁻¹, and 0.141 kJ mol⁻¹K⁻¹ for Pb (III), respectively. ΔH° values (46.01 kJmol⁻¹) showed that the adsorption mechanism was endothermic. Weber‐Morris and Urano‐Tachikawa diffusion models were also applied to the experimental equilibrium data. The fish bones were effectively used as sorbent for the removal of Pb (II) ions from aqueous solutions.