A simple, precise, accurate, robust, and stability-indicating reverse phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous estimation of Ceftriaxone Sodium and Sulbactam Sodium in bulk and pharmaceutical dosage forms. The chromatographic separation was achieved using an Inertsil ODS C18 column with a mobile phase consisting of phosphate buffer (pH 3.5) and acetonitrile in the ratio of 60:40 v/v under isocratic conditions. The flow rate was maintained at 1.0 mL/min, and detection was carried out at 254 nm using a UV detector. The developed method produced sharp, symmetrical, and well-resolved peaks with retention times of 3.89 min for Sulbactam Sodium and 7.52 min for Ceftriaxone Sodium. The method was validated according to ICH Q2(R1) guidelines for system suitability, specificity, linearity, precision, accuracy, robustness, ruggedness, limit of detection (LOD), and limit of quantitation (LOQ). The calibration curves showed excellent linearity over the concentration ranges of 25–150 µg/mL for Ceftriaxone Sodium and 10–60 µg/mL for Sulbactam Sodium, with correlation coefficients close to unity. Accuracy studies demonstrated satisfactory recovery values within acceptable limits, while precision studies showed low %RSD values, confirming the reproducibility of the method. Forced degradation studies established the stability-indicating capability of the developed method. The method was successfully applied for the analysis of marketed injectable formulations without interference from excipients. Overall, the developed RP-HPLC method was found to be reliable, sensitive, and suitable for routine quality control and stability studies of Ceftriaxone Sodium and Sulbactam Sodium.