The use of nanoparticles in treating dreadful diseases like cancer is the emerging field of research in cancer therapy. In the present investigation, the green biosynthesis of silver nanoparticles (AgNPs) with aqueous fruit extract of Terminalia belarica has been carried out, and ultraviolet-visible spectroscopy (UV-Vis) analysis was done which revealed an intense surface plasmon resonance (SPR) band at 430 nm, thus confirming the formation of Tb-AgNPs. The AgNPs were further characterized by Fourier transform-infrared spectroscopy (FTIR), showing the reduction of silver nitrate into Tb-AgNPs by the reduction of different functional groups such as hydroxyl, phenols, stretch of aldehydes, alkenes and aromatics. Transmission electron microscopy (TEM) and diffraction light scattering (DLS) study showed that the nanoparticles were round in shape with an average size of 46.5 nm. The atomic force microscopy (AFM) analysis also revealed similar results to facilitate that the AgNPs were round in shape, and the size was calculated by Z-coloration method. Furthermore, the X-ray diffraction (XRD) data confirmed that Tb-AgNPs were crystalline with face centered cubic (fcc) structure and were very stable with −29.1 mV Zeta potential. Tb-AgNPs showed efficient free radical scavenging activity against 2, 2-diphenyl-1-picrylhydrazyl, hydrogen peroxide and nitric oxide. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method was the best among the three antioxidant methods with the half maximal inhibitory concentration (IC₅₀) value of 47.25 ± 0.17. Tb-AgNPs also showed superior and efficient antibacterial activity greater than the control antibiotic, and showed effective anti-proliferative and cytotoxic effect on human breast cancer cells with IC₅₀ value of 73.18 µg/mL. The biosynthesized Tb-AgNPs with multifunctional properties could be employed as a source for the exploration of novel therapeutic antioxidant, antibacterial and anticancer agent.