This study demonstrates for the first time the potential of the novel combination of aluminum (Al) doping and amino functionalization to drastically enhance the adsorption capacity of nanosheet-assembled hierarchical calcium silicate hydrate (CSH) architectures for heavy metal Pb2+ and Cu2+ ions in aqueous solution. The designed and prepared amino-functionalized Al-doped CSH (CASH-NH2) exhibits excellent adsorption capability to adsorb Pb2+ and Cu2+ ions. The maximum adsorption capacity of Pb2+ and Cu2+ ions is 911 and 509 mg g−1, respectively, which is much higher than that of pure CSH and other relative CSH-based adsorbents. The experimental measurements of cation exchange capacity (CEC) and surface composition discover that the adsorption of Pb2+ and Cu2+ ions on CASH-NH2 is preponderantly achieved by the cation exchange and surface complexation, in which Al doping substantially enhances the exchange capacity between Ca2+ of CSH and Pb2+ or Cu2+, and the functional amino groups chelate Pb2+ or Cu2+ to realize surface complexation of CASH architectures. Thereby the excellent adsorption performance of CASH-NH2 is attributed to the significant enhancement in the CEC between Ca2+ of CASH and Pb2+ or Cu2+, and the amino functionalization-induced surface complexation of the CASH, which are achieved by the synergistic effect of Al doping and amino functionalization. This work opens a new way for simultaneously exploiting metal doping and amino functionalization to boost the adsorption performance of other adsorbents to achieve highly efficient removal of toxic cationic species from polluted water.