Enhancing the energy storage capabilities of supercapacitors (SCs) while preserving their electrochemical performance is crucial for their widespread application. Our research focuses on developing Sb-modified tin oxide (ATO) nanoparticles via a scalable hydrothermal process, offering substantial potential in this domain. The tetragonal nanoparticle structure provides abundant active sites and a highly porous pathway, facilitating rapid and efficient energy storage. Additionally, tin's varied oxidation states significantly enhance redox capacitance. Electrochemical measurements demonstrate ATO's promise as an advanced SC electrode, achieving a peak specific capacitance of 332 F/g at 3 mA/cm2, with robust redox capacitance confirmed through kinetic analysis. Moreover, the ATO electrode exhibits exceptional capacitance retention over 2000 cycles. This study establishes ATO as a leading candidate for future energy storage applications, underscoring its pivotal role in advancing energy storage technologies.