Spherical biogenic silver nanoparticles (AgNPs) were synthesized using aqueous green coffee bean extract as a reducing agent. The green coffee bean extract was used for the time to reduce silver ions via a one-step, green, and rapid approach. The prepared AgNPs were characterized via transmission electron microscopy (TEM), atomic force microscopy (AFM), and UV-visible spectroscopy. Dynamic light scattering (DLS) was performed to measure the particle size. These AgNPs exhibit strong antibacterial activity against both Gram-negative and Gram-positive bacteria and the minimum inhibitory concentration (MIC) of AgNPs for Escherichia coli and Staphylococcus aureus are 0.05 μmol L⁻¹ and 0.1 μmol L⁻¹, respectively. Furthermore, AgNPs could serve as an effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH₄.