Abstract: Background and Objective: The green synthesis of the metallic nanoparticle by bioreduction is simple, economical, eco-friendly and cost-effective. Synthesis of metallic nanoparticles using plants contains several phytochemical compounds which are functionalized to nanoparticles. The main goal of this study is to synthesize silver nanoparticles using the aqueous extract obtained from the stem of Cissus quadrangularis and their anticancer activity on the HT29 colon cancer cell line. Materials and Methods: Silver nanoparticle was characterized by UV-visible spectroscopy, scanning electron microscopy, Fourier Transform Infrared (FTIR) spectroscopy etc. The cell viability and cytotoxicity of Ag-NP-CQ was confirmed by Trypan blue and MTT assay, in a dose-dependent manner. The apoptotic inducing ability of Ag-NP-CQ was investigated by ROS and NO estimation, propidium iodide staining and BAX and PARP gene expression by Polymerase Chain Reaction (PCR). Results: Results showed a greater reduction in viability of cells exposed and increasing cytotoxicity to green Ag-NP-CQ with increasing dose. Our data confirmed that Ag-NP-CQ enhances the antioxidant activity by scavenging the free radicals. Elevated apoptotic protein BAX with down regulated PARP was observed in Ag-NP-CQ treated cells regulates its anticancer effect through apoptotic signalling pathways. Conclusion: Based on the above findings biosynthesized silver nanoparticles with Cissus quadrangularis are very effective against colon cancer cell lines proving or exerting their anti-cancer activity.