<p>High-performance supercapacitors are essential for advancing energy storage devices, and superior active materials are crucial for this purpose. W₁₈O₄₉ is recognized as a highly promising electrode material, such as in the form of nanowires and nanorods, for energy conversion and storage. However, it still faces challenges like low conductivity and insufficient active sites. The strategy of heteroatom doping has shown effectiveness, such as tin (Sn), which has potential for enhancing matrix performance, but it has not been explored for W₁₈O₄₉ materials. Herein, a series of Sn-doped W₁₈O₄₉ materials are carefully designed and synthesized using a straightforward one-pot solvent-thermal method in this study. Various analyses are conducted to confirm successful Sn doping and to observe structural changes with different Sn concentrations. The optimal material is identified as 3% Sn-W₁₈O₄₉, which displays a unique 3D sea urchin-like structure as observed via SEM and TEM. Furthermore, XRD peaks related to SnO impurities are noted at higher Sn doping levels, such as 5% and 7% Sn-W₁₈O₄₉. Electrochemical testing reveals a high specific capacitance of 546 F∙g⁻¹ at 4 A∙g⁻¹ for the 3% Sn-W₁₈O₄₉ electrode, alongside excellent long-term cycling stability with an 86% capacitance retention after 6000 GCD cycles. The enhanced performance is attributed to the improved electrical conductivity, surface area, and active sites of the W₁₈O₄₉ through optimal Sn doping. This research highlights the promising electrochemical properties of Sn-doped W₁₈O₄₉ materials.</p>