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Graphical abstract Abstract Design and fabrication of materials with abundant functional groups represent an important and promising direction in the remediation of aqueous contaminants. In recent years, carbon-based materials have drawn widespread concern on account of their low cost, large specific surface area, good chemical stability as well as controllable porosity. The U(VI) binding onto raw carbon-based materials is still confronted with the problem of limited adsorption capacity, which severely hinders the practical applications of materials. Herein, amino- and carboxyl-functionalized carbonaceous spheres (denoted as ACSs and CCSs) were fabricated by in-situ polymerization and simply annealing methods, respectively. The highest adsorption amounts of ACSs and CCSs towards U(VI) were calculated to be 73.83 and 401.61 mg·g−1 from Langmuir model at pH = 4.0 and 298 K, which were higher to that of raw carbonaceous material (19.31 mg·g−1). Interestingly, the Freundlich model could well simulate U(VI) sorption isotherms on ACSs at these temperatures (T = 298, 313 and 328 K), while U(VI) sorption isotherms on CCSs were able to significantly conform to the Langmuir model. According to FT-IR and XPS analysis, U(VI) was enriched on both materials on account of the ample functional groups on ACSs (e.g. C NOH/C NH 2) and CCSs (e.g. OH/COOH). In addition, effect of ionic strength manifested that U(VI) elimination on ACSs and CCSs were greatly caused by the formation of outer-sphere and inner-sphere surface complexes, respectively. This work promises to provide two facile approaches for engineering diverse functionalized materials towards a highly rapid and efficient sequestering U(VI) from contaminated water. [ABSTRACT FROM AUTHOR]