Nanocomposites of intertwined multi-walled carbon nanotubes (MWCNTs) and MoO3 nanowires were synthesized using a hydrothermal method. The intercalation of MWCNTs with MoO3 nanowires made them excellent materials for viable supercapacitors with high energy and power densities. The specific capacitance of the intertwined MoO3–MWCNTs nanocomposite reached 210Fg−1, and the energy density was improved greatly to 71.6Whkg−1 with a power density of 600Wkg−1 compared to those of pristine MWCNTs and MoO3 nanowires. The composite electrodes exhibited an excellent charge/discharge rate and long-term cyclic stability in terms of capacitance with an efficiency of more than 95% after 2000 cycles. These findings open up the possibility of intertwined MoO3–MWCNT composites being utilized in safe aqueous electrolyte (Na2SO4)-based high-voltage supercapacitors with high energy and power densities.