Aim: The aim of work is to develop and validate simple, specific, accurate, precise HPLC method for the estimation of Curcumin (CUR) and Thymoquinone (THQ) simultaneously in bulk and its formulation as per ICH guidelines for analytical method development and validation. Study Design: Developing RP-HPLC method using C-18 Inertsil column and optimization of variables for estimation of Thymoquinone and Curcumin in bulk and formulation. Place and Duration of Study: The present work was carried out at Shri D. D. Vispute College of Pharmacy and Research Center, Panvel in year 2021. Methodology: The RP-HPLC method was developed with an isocratic condition of mobile phase comprising acetonitrile and water in a ratio of (82:18) v/v, at a flow rate of 0.9 mL/minute over Inertsil ODS, 250× 4.6 mm, 5 µm column, at 30°C column oven temperature. Photodiode array at 256 nm was used for detection Results: Retention time for curcumin and thymoquinone was found to be 3.5 and 4.3 mins respectively. The method showed excellent linear response in concentration range of 4-18 µg/mland 10-45 µg/mlfor thymoquinone and curcuminrespectively with correlation coefficient (R2) values of0.999 for both. System precision and method precision studies were less than the maximum allowable limit percentage of relative standard deviation ≤ 2.0 i.e., 1.61 % and 1.62 % for curcumin and 0.47 % and 0.42 % for thymoquinone respectively. Mean % Recovery for both the drugs were within acceptance limits. The developed and validated HPLC method is simple, accurate, precise and suitable for analysis as all the results were within acceptance criteria. Conclusion: The developed RP-HPLC method at single wavelength was validated according to ICH guideline with respect to system suitability, specificity, linearity, accuracy, precision and robustness and can be used for routine quality monitoring of drug in pharmaceutical dosage form.