The FDA-approved antiviral drug molnupiravir (MPV) was investigated using a green spectrophotometric approach. With the help of mass spectrometry, UV-visible spectroscopy, and Infrared Fourier transform spectroscopy, this drug was characterized and elucidated structurally. This approach depends on measuring the absorbance in doubly distilled water as a solvent at 240 and 285 nm. Variable parameters were estimated and optimized. Beer's law is up to 35.0 µg/mL under optimal conditions with a correlation coefficient (r2)>0.99. Based on this evaluation, the new method was found to be highly sensitive with a LOD and LOQ of 0.34-0.78 and 1.13-2.59 µg/mL, respectively. Analyses provided reproducible results with a 2.0% relative standard deviation (RSD). As a result of the application of the proposed method, MPV levels were successfully achieved in raw materials, pharmaceutical formulations, and biological fluids. The geometry and energy quantum mechanical calculations were also performed using Becke's three-parameter exchange functional method. Using water as a solvent, Lee-Yang-Parr correlation functional analysis (B3LYP/DFT) confirmed the measured results.