A simple, specific, sensitive, robust, accurate and precise reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for simultaneous determination of sofosbuvir (SOF) and velpatasvir (VLP) in fixed dose combination tablets and plasma. Validation parameters, such as system suitability, accuracy, inter-day and intra-day variances, specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), robustness and stability were assessed following the standards set by the International Conference on Harmonization (ICH). The isocratic elution of SOF and VLP was carried out under ambient conditions using ammonium acetate buffer (pH = 7.0), acetonitrile and methanol (20:40:40, v/v/v) as mobile phase flowing through a Promosil C18 column at a flow rate of 1.0 mL/min. The average retention time of SOF and VLP was 3.72 min and 7.09 min, respectively. The LOD and LOQ of SOF were 0.23μg/mL and 2.48μg/mL, respectively; while those of VLP were 0.70μg/mL and 7.52μg/mL, respectively. The regression coefficient (r2) was 0.998. The relative standard deviation (RSD) was less than 2% for precision. The recovery of both the analytes remained within 100±1%. All other validation parameters complied with ICH guidelines. The analytes remained stable throughout the analytical procedure. Moreover, this method was successfully applied to assess the in vitro dissolution of SOF and VLP loaded fixed dose combination tablets. Same method with same mobile phase was applied on rat plasma and there was no interference.