Ultrathin antimony trioxide (Sb 2 O 3 ) was synthesized on ITO substrate by solvothermal method using ethanol as asolvent. The structure, morphological variations and optical properties of the as-prepared sample were characterized.The results indicated that the homogeneously grown sheet of cubic phase of ultrathin Sb 2 O 3 have elliptical crosssection with thickness of 20 nm and diameter of 400-500 nm. Further, an ultraviolet (UV) performancephotodetector based on the (Au/Sb 2 O 3 /Au) was fabricated and examined. The measured Current Voltage (IV) curvesin the dark and under illumination (UV-395 nm) of different intensities indicate the presence of Schottky barrier atthe interfaces between Sb 2 O 3 and Au-electrodes. Photocurrent values of 2.32, 16.5, and 25.58 μA were obtained forintensities of 4, 8 and 12 mW/cm 2 , respectively at bias voltage of +3V, as compared to dark current of 0.78μA.Sensitivity and responsivity values of 40.04 and 6.294W/A were recorded. The current-time (I-T) graph was utilizedto derive the response and recovery times of the sensor under chopped UV-laser at different power intensities. Thesensor exhibited fast response and recovery times of 113.6 ms and 67.2 ms, respectively, making this a high-performance sensor. This study demonstrates that ultrathin Sb 2 O 3 nanosheet can be very useful to develop simpleand high-performance UV sensors in different commercial fields and industries in the future.