An accurate, rapid, and simple UPLC method was developed and validated for simultaneous determination of atazanavir and ritonavir in formulations. The separation was established on a column BEH Shield C18 (50 × 2.1 mm; 1.7 µm) connected at 30 °C. The detector (PDA) was set at 249 nm. The mobile phase consisted of 5% acetonitrile in methanol and 10mM ammonium formate (pH = 4.0; 0.1% formic acid) in a gradient mode. The flow rate was set at 0.3 mL/min. The retention times of atazanavir and ritonavir were 0.321 and 1.779 min, respectively. The proposed method demonstrated linearity in the ranges of 6-36 µg/mL for atazanavir and 2-12 µg/mL ritonavir. The coefficients of determination (R2) were greater than 0.999, with percentage recoveries greater than 98-102% for each drug. The proposed method was highly precise, as indicated by the low percentage of relative standard deviation values of less than 2% for each drug. The method had the requisite accuracy, precision, and robustness for simultaneous determination of atazanavir and ritonavir. The proposed method could be successfully employed in routine quality control for the simultaneous analysis of atazanavir and ritonavir n pharmaceutical formulations