The inherent limited energy density in supercapacitors constitutes a substantial impediment to their widespread adoption and large-scale production. In this study, we have devised a novel cathodic electrode denoted as OV-TiO2-X@HPHCFP, featured with rich oxygen vacancies and its hierarchical porous hollow structure. The OV-TiO2-X@HPHCFP cathode manifests an impressive areal capacitance of 1608.2 mF cm−2 at the current density of 2 mA cm−2, coupled with a remarkable capacitance retention of 97.7 % after 10,000 charge–discharge cycles. Theoretical calculations corroborate that the presence of oxygen vacancies enhances the conductivity of the electrode, facilitating expedited charge transfer kinetics. Furthermore, the electrode integrated into a double electrolyte flexible supercapacitor configuration, denoted as OV-TiO2-X@HPHCFP//PVA-Na2SO4/PVA-LiCl//OV-MoO3-Y@CFP, operated at an effective potential of 2.5 V, can yield an energy density of 1.96 × 10−1 mWh cm−2 at a power density of 1.25 mW cm−2. This investigation thereby delineates a promising strategy for the development of supercapacitors that can attain elevated operational potentials with concomitant enhancements in energy density.