Antibacterial starch-silver nanoparticles (ST-AgNPs) for use as coating solutions were prepared in a single step by ultrasonicating a mixture of starch, silver nitrate, and distilled water. The starch was used as an eco-friendly and inexpensive reducing agent. UV–vis spectra and transmission electron microscopy indicated that our single-step process was effective for synthesizing starch-based coating solution with AgNPs. Further, the as-prepared coating solution with AgNPs was applied to expand the application of paper for antibacterial packaging. The starch-coated paper with AgNPs showed not only highly enhanced oil resistance, but also excellent antibacterial activity, making our biodegradable starch-coated paper with AgNPs highly feasible for packaging applications.