The purpose of this study was to analyse the probable phytochemical compounds that were in the leaf extract of a shrub known as Cajanus trinervius (CT). We achieved this by using the gas chromatography–mass spectrometry (GC-MS) method in polar solvents like methanol, personal ether and ethanol. We evaluated the crude sample in a variety of solvents and found several distinct chemicals, including phenolics, terpenoids, flavonoids, carbohydrates, amino acids, glycosides, proteins, steroids, tannins and alkaloids. According to the outcomes of the GC-MS analysis, the mediums containing methanol, ethanol and pet ether each included 78, 82 and 38 chemical components, respectively. Sesquiterpenoids, phenolic compounds, amino substances and long-chain hydrocarbons were the most abundant chemicals. The outcomes of the experiment, along with the presence of a variety of phytochemicals in this plant, encouraged us to carry out the microwave synthesis of silver nanoparticles from this leaf extract and analyse them. We used the MTT test on the A431 cell line, to assess the damaging effects of aqueous CT extracts and CT-Ag NPs. Dual and DAPI staining confirmed the apoptotic activity of Cajanus trinervius leaf extract along with their ROS release assessment confirmation by DCFDA staining.