Nanotechnology is an attractive research field due to the production of nanoparticles in different sizes, shapes, chemical compositions, and distributions, and their many applications for humans. The fabrication, manipulation, and use of metallic nanoparticles are of great importance due to their reduced dimensions and, as a result, their unique thermal, optical, and electronic properties. Most nanoparticle synthesis techniques are inefficient considering material and energy consumption. In most chemical methods, dangerous chemical materials to humans and the environment are used. Accordingly, there is a demand for nanoparticle production using biological methods. Biological production methods for nanoparticles have priority over physical and chemical methods considering energy cost, time reduction, and use of natural solvents. Meanwhile, silver nanoparticles are one of the most commercial nanomaterials. In this research, silver nanoparticles were produced using extract of thyme plant with biological methods without using any chemical materials. Various synthesis parameters such as temperature, pH, and synthesis time were optimized. The synthesized nanoparticles were characterized by various methods including ultraviolet-visible spectroscopy, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and zeta potential. The synthesized nanoparticles are spherical, with a mean diameter of 38.9 ± 10.4 nm (range 20–60 nm) as measured by TEM. Biosynthesis of silver nanoparticles using thyme extract is a successful, cost-effective, and time-efficient method.