Silver nanoparticles incorporated into magnetic nanocomposite were synthesized using a crude methanolic extract from Piper solmsianum, which was used as an agent for reduction and stabilization in phytochemical-assisted synthetic nanomaterial. The antimicrobial activity of the pathogenic microorganisms is reported here. The synthesized nanoparticles were also characterized by transmission electron microscopy and quantification of Ag analysis. The antimicrobial activity was evaluated by the broth microdilution method, against the bacteria Bacillus subtilis, Staphylococcus aureus and Escherichia coli, and the yeast Candida albicans. Among the nine compounds tested, CMAgPs2 and CMAgPs5 presented the best results in terms of activity against bacteria (bactericidal) and yeast (fungistatic). It was observed that crude methanolic extract proved to be a potential reducing agent for green synthesis. It was also found that no CMAgPs sample was toxic in the Artemia salina test.