A series of monolithic supermacroporous hydrogels with three-dimensional structured polymeric network were successfully formed via thermal-initiated high internal phase emulsions (HIPEs) technique by grafting acrylic acid (AA) chains onto the backbone of chitosan (CTS), and then used as the adsorbents to remove Cu²⁺ and Pb²⁺ ions from the wastewater. The effects of pore structure of the as-prepared monolithic hydrogel, as well as external adsorption conditions including pH, initial concentration and contact time on the adsorption properties were systematically investigated. The results indicated that the presence of porous structure of these monolithic supermacroporous hydrogels was responsible for the fast adsorption kinetics, allowing the adsorption system to be finished within 5 min for Cu²⁺ and Pb²⁺ at the low concentration of 50 mg/g, and 20 min for Cu²⁺ and Pb²⁺ at the high concentration of 500 mg/g. In addition, these adsorbents exhibited higher adsorption capacity of 302.01 mg/g for Cu²⁺ and 611.94 mg/g for Pb²⁺ in the optimized pH range of 4–6, and the adsorption capacity had a slight decrease after five adsorption–desorption cycles, an indication of their excellent reusability. All the information revealed that these monolithic hydrogels with rich pore hierarchy are expected to show their potential application for highly efficient removal of Cu²⁺ and Pb²⁺ from aqueous solution.