Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO (α, γ) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the α-GOM (the weight ratio of GO/α-MnO of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5 mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on α-GOM was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and α-GOM. Finally, the Th(IV)/U(VI) ions on α-GOM can be separated by a two-stage desorption process with NaCO/EDTA. Those results displayed that the α-GOM may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions.