The paper reports an efficient and rapid fast LC method for estimation of diclofenac potassium and its impurities. The main aim of the study is to develop and validate a simple, rapid, accurate, sensitive, less time consuming and less expensive method by using RP-HPLC with UV detector. The chromatographic separation of diclofenac potassium and its impurities was carried out by using 150 × 4.6 mm, i.d., 5 μm C-18 column with prepared mobile phase-A consisting 800:200 (v/v) of 0.01 M ammonium acetate adjusted pH 5.3 with acetic acid and acetonitrile and mobile phase-B consisting 200:800 (v/v) of 0.01 M ammonium acetate adjusted pH 5.3 with acetic acid and acetonitrile. The wavelength for detection of were made at 280.0 nm using UV detector. The flow rate of 1 mL/min. The method was able to detect and separate impurities and diclofenac potassium. The system suitability parameters were found within the limits. The coefficient of correlation for diclofenac potassium and its impurities was found not less than 0.998. The %recovery was found within the ICH limits. The LOD and LOQ values from study demonstrate method is sensitive. The method was validated for linearity, precision, accuracy, specificity, intermediate precision, ruggedness, robustness, stability and suitability.