The objective of this study is to develop a novel, rapid and  sensitive UV spectrophotometeric technique for the determination of Fostemsavir in bulk and pharmaceutical dosage form . The solvent used was phosphate buffer pH 6.8 and the maximum absorbance  was recorded at 278 nm. Analytical calibration curves were linear within a concentration range of 7.5 to 45?g/ml and coefficient of correlation 0.999. The percentage RSD was found to be less than 2. The result of analysis has been validated statistically. This method was validated in accordance with ICH requirements which included the  parameters like linearity, accuracy ,precision, sensitivity, specificity and robustness. Hence the proposed method can be used for the reliable quantification of Fostemsavir in bulk and tablet formulation. The present outcome of research summarizes that the method is suitable for routine analysis for the determination of Fostemsavir.