Spectrophotometric analysis has proven to be one of the most referred analytical techniques available; as the enlarged globalization of the pharmaceutical market has reduced the availability of quality pharmaceuticals at minimal cost. Authors have made an attempt for development and validation of simple UV- spectrophotometric area under curve (UV -AUC) method for quantitative estimation of atazanavir sulfate in bulk and in a pharmaceutical formulation. To enhance accuracy, additional attempts were made for the measurement of uniform area around the wavelength maximum (248 nm) and in between the designated wavelengths (238 nm and 260 nm). The mixture of methanol and water in a proportion of 30:70 v/v was selected as a solvent system. Efficient correlation between the concentration and corresponding response was maintained by measuring the uniform area under the peak obtained at the wavelength maximum. The calibration plot for the method was constructed by plotting the values for AUC obtained for the concentration range of 6 - 36 μg/mL with a correlation coefficient of 0.999. Developed method was validated on the basis of ICH Q2 R1 guideline. The method depicted good reproducibility with percent RSD less than 2.0. Estimation of atazanavir sulfate by aforementioned method in bulk and capsules was carried out efficiently.