A precise and robust method was developed method for the estimation of Ceftolozane and Tazobactam in pharmaceutical dose form and bulk. Agilent 1260 Infinity II model HPLC with DAD detector and Phenomenex Kinetex XB-C8 with dimensions of 150 x 4.6 mm, 5 µm was utilized in the method. The Mobile phase combination used was 0.1% Trifluoroacetic acid and Acetonitrile (70:30). The retention time of Ceftolozane (TOL) and Tazobactam (TAZ) peaks was at 3.05 and 3.96 minutes, respectively. In compliance with ICH Q2 (R1) requirements, the devised approach was validated. The instrument precision for TOL & TAZ had a %RSD of 0.66% and 0.68%, respectively. The Intra & Inter day precision for TOL & TAZ had a %RSD of 0.74% and 0.24%, respectively The linear and accurate method was applied to concentration ranges of 80-120 µg/ml and 40-60 µg/ml for both TOL and TAZ, respectively. The regression coefficient for both TOL and TAZ was 0.999 and % RSD for accuracy for TOL at 80%, 100% and 120% was found to 0.82%, 0.93% and 0.12% respectively; and for TAZ at 80%, 100% and 120% was found to be 0.33%, 0.89% and 0.55% % respectively. The LOD & LOQ for TOL are 1.65 g/ml and 4.99 g/ml respectively and the LOD & LOQ for TAZ are 1.41 g/ml and 4.26 g/ml respectively.