A simple, precise, and stability-indicating RP-HPLC method was developed and validated for the quantitative determination of Dexlansoprazole in bulk drug and capsule dosage form. Chromatographic separation was achieved on an Inertsil ODS C18 column (250.0 x 4.6 mm, 5.0 um) using a mobile phase of phosphate buffer (pH 7.0) and acetonitrile (55: 45 v/v) at a flow rate of 1.0 ml/min with UV detection at 285 nm. The method was validated in accordance with the ICH guidelines for specificity, linearity, precision, accuracy, and robustness, range, and system suitability. The method exhibited excellent specificity with no interference from excipients or degradation products. Linearity was observed over the selected concentration range with a high correlation coefficient. Precision and accuracy studies showed relative standard deviation values within acceptable limits, confirming methods reliability. Robustness testing demonstrated the method's consistency under small deliberate variations. The validated method is suitable for routine quality control analysis of Dexlansoprazole in bulk and capsule formulation.