<p>To investigate the influence of structural defects on the electrochemical performance of TiO₂ for supercapacitor applications, we develop two synthetic strategies: a hydrothermal method and a post-synthetic chemical reduction for controlled oxygen defect implantation. These methods yield two-dimensional TiO₂ nanosheets with uniformly distributed defects located in the bulk, on the surface, or in both regions simultaneously. Detailed characterization using X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and ultraviolet–visible (UV–Vis) spectroscopy confirms the formation of the anatase phase TiO₂ with controlled defect engineering. The electrochemical behavior was systematically investigated through cyclic voltammetry, constant-current charge–discharge measurements, and impedance analysis performed in a three-electrode configuration employing 3&#xa0;M KOH as the aqueous electrolyte, revealing that the NaBH₄-annealed TiO₂ delivered a maximum specific capacitance of 297 F g⁻¹ at 2 A g⁻¹ and 66.5% retention after 5000 cycles. The observed improvement in electrochemical performance originates from the synergistic effects of enhanced electrical conductivity, a higher density of redox-active sites, and facilitated ion diffusion enabled by the defect-enriched architecture. These results highlight a facile strategy to enhance TiO₂-based electrodes for next-generation energy storage devices.</p>