Resveratrol and piperine are proven for their therapeutic benefits to treat various diseases. Due to their synergistic actions and combined drug delivery application, a rapid and specific RP-HPLC method was developed and validated as per ICH guidelines, by using an isosbestic point. The chromatographic separation was performed with Luna 5 μ 100 Å C-18(2) HPLC column by using acetonitrile (ACN): phosphate buffer (0.01% orthophosphoric acid) (55:45) as mobile phase, at 1 mL/min of flow rate and 330 nm. The developed method was found to be linear over the concentration range of 0.25-8 μg/mL with correlation coefficient value0.999. The developed method was accurate (percent recovery 98.06-101.74%), precise (percent relative standard deviation2.0%), and robust. The limit of detection and limit of quantification for resveratrol were found to be 0.02 and 0.08 μg/mL, respectively and 0.04 and 0.11 μg/mL, for piperine, respectively. The developed method was also validated in human plasma as per ICH guidelines. Moreover, stress degradation studies of both phytoconstituents were studied and the relevancy of the developed method was analyzed on cubosome nanoformulation. A good separation of drug peaks was observed in the presence of the degradation products. This method could thus be used for regular in vitro and in vivo estimation of piperine and resveratrol.