<p>To overcome worldwide challenges in energy sustainability and environmental protection, there is a strong need for next-generation electrode materials and solar-responsive photocatalysts. Progress in supercapacitors and wastewater treatment relies on continual innovation in eco-friendly, high-performance materials. In this regard, this work reports the successful synthesis of two distinct bismuth tungstate phases, Bi₂WO₆ and Bi₂W₂O₉, via a facile gel matrix approach. The structural and spectroscopic analyses, including x-ray diffraction (XRD) and Raman spectroscopy, confirmed their single-phase formation and vibrational characteristics. The oxidation states of the elemental components were verified by x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) imaging of the synthesized bismuth tungstate nanomaterials revealed distinct surface morphologies. Brunauer–Emmett–Teller (BET) analysis was performed to investigate surface area and pore size of the synthesized bismuth tungstate phases. Electrochemical investigations revealed that Bi₂W₂O₉ outperforms Bi₂WO₆, showcasing a higher capacitance of 986 F g⁻¹. Harnessing this, an asymmetric supercapacitor employing Bi₂W₂O₉ as the positive electrode paired with activated carbon demonstrated remarkable energy storage capabilities, achieving an energy density of 20 Wh kg⁻¹ at 750 W kg⁻¹ power density with outstanding cycling stability. Beyond its role in energy storage, Bi₂W₂O₉ exhibited a markedly higher efficiency in light-assisted breakdown of methylene blue than Bi₂WO₆, reflecting its diverse functional capabilities. These findings highlight Bi₂W₂O₉ as a cost-effective, high-performance material platform that bridges advanced energy storage and environmental remediation in a single versatile nanostructure.</p>