The present LC-MS/MS method for the estimation of Metformin in human plasma by using Doravirine as an internal standard was established and validated as per ICH guidelines. The best response was obtained with Phenomenex Synergi, 4µm, 4.6×75mm, and a mobile phase containing a mixture of 5mM Ammonium Acetate buffer with 0.1% Formic Acid: Acetonitrile (40:60 v/v) was delivered at a flow rate of 1.0 mL/min by positive ion mode (API 4000Q Trap) with an injection volume of 25 µL and a run time of 20min. Detection is performed by atmospheric pressure electrospray ionization (ESI) tandem mass spectrometry in positive ion mode. The precursor to product ion transitions is m/z452.42>71.32 for Metformin and m/z 271.2>228.8 for Doravirine (Internal standard) were used for quantization. The retention time of Doravirine (Internal standard) and Metformin was found to be 1.56 min and 7.04 min respectively. This method development Stable, Robust, Reproducible and Capable of producing reliable results.