The mesoporous ATO/MnO2 core–shell architectures are prepared through a one-pot templated-assembly route. The morphologies and structures of ATO nanoparticles and ATO/MnO2 nanocomposites are examined by focus ion beam scanning electron microscopy (FIB/SEM) and X-ray diffraction spectroscopy (XRD). Furthermore, the electrochemical properties of the ATO/MnO2 nanocomposites electrodes are elucidated by cyclic voltammograms, galvanostatic charge/discharge tests and electrochemical impedance spectroscopy in 1M Na2SO4 electrolyte. The results demonstrate that the ATO/MnO2 nanostructure electrodes exhibit highly reversible features, good specific capacitance (186.8Fg−1), and good capacitance retention (76.8% over 1000 cycles). Indeed, the ATO nanoparticles provide a high conductivity for core–shell architectures. These findings indicate the suitability of the low-cost ATO/MnO2 nanocomposites as a potential electrode material for supercapacitors.