In this study silver nanoparticles (AgNPs) were synthesized using water extract of the aerial parts of Euphorbia paralias (E. paralias) as reducing and stabilizing agents. Various experimental parameters, including sample pH, temperature, reaction time, extract composition, and metal salt concentration, were examined for their effects on the size and morphology of the AgNPs. The synthesized silver nanoparticles (AgNPs) were characterized using UV-Vis spectroscopy, FTIR, X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermal gravimetry. The formation of AgNPs began within 3 minutes and progressively increased over time for two hours. The synthesized nanoparticles were predominantly spherical, with an average size varying between 15 and 35 nm. Bio-fabricated AgNPs have more significant anticancer activity against HepG2, MCF-7, and HCT-116 with IC50 = 20.3 ± 1.8, 30.4 ± 3.8, and 45.2 ± 2.5 µg/ml respectively. The anticancer activity of the aqueous extract of Euphorbia paralias with IC50 > 500 µg/ml indicates that AgNPs exhibit synergistic effects as the diverse range of phytochemicals present in plant extracts, combined with the small size and large surface area of AgNPs, allows for maximum adsorption of these capping agents onto their surfaces and improves the therapeutic performance of phyto- AgNPs in anticancer activity.