The integration of green nanotechnology with traditional medicinal plants offers a sustainable platform for designing multifunctional nanomaterials. In this study, we report the phytosynthesis of silver nanoparticles (AgNPs) using hydroethanolic extracts of Cecropia peltata L., a neotropical species endemic to the Ecuadorian Amazon and recognized for its ethnopharmacological relevance. The biosynthesized nanoparticles (Cp-AgNPs) were characterized using XRD, SEM, EDS, TEM, DLS, UV-Vis, and FTIR. Phytochemical analysis of the C. peltata extract revealed high contents of ferulic acid, p-hydroxybenzoic acid, and other flavonoids and phenolic acids, which could act as natural reducing and capping agents. The Cp-AgNPs exhibited potent and broad-spectrum antimicrobial activity against clinically relevant strains, with a minimum inhibitory concentration (MIC) of 6 µg/mL against Staphylococcus aureus and strong inhibition of multidrug-resistant (MDR) strains, including Pseudomonas aeruginosa and Enterococcus faecium, which represent urgent global health threats. Cp-AgNPs showed minimal hemolytic toxicity, underscoring their biocompatibility. These findings demonstrate that C. peltata L.-derived silver nanoparticles represent a green and promising alternative for the development of safe and efficient antimicrobial nanomaterials, particularly for applications in biomedicine and infection control. Furthermore, the work highlights the value of underexplored Amazonian flora as a source of bioactive compounds for the sustainable production of next-generation nanomaterials.