Mesoporous MnO₂/SBA-15 composites were prepared via a simple route using KMnO₄ and MnCl₂ as Mn sources for the first time and were explored as a synergetic adsorbent for the removal of U(VI). The results demonstrated that the U(VI) adsorption capacity of both pristine SBA-15 and MnO₂ can be greatly enhanced by combining them. MnO₂/SBA-15 composites exhibited remarkable U(VI) adsorption capacity. The 40%MnO₂/SBA-15 sample with optimum MnO₂ content exhibited a maximum U(VI) adsorption capacity of 465.1 mg g⁻¹, which is much higher than those of pristine SBA-15, MnO₂ and many other adsorbents. The U(VI) adsorption process was well fitted by the Langmuir model and the pseudo-second order model. The thermodynamic data analyses revealed that the U(VI) adsorption process was spontaneous and endothermic. It was proposed that the synergetic effect played an important role in the U(VI) adsorption process. These results demonstrated that the MnO₂/SBA-15 composites can be employed as a promising U(VI) adsorbent.