Silver nanoparticles (AgNPs) are amongst the most fascinating nanomaterials which have been extensively synthesized by chemical reduction and biological method using enzymes, microorganisms and plant extracts. In our study, an aqueous extract of green tea was used as a stabilizing and reducing agent for AgNPs synthesis. The synthesized AgNPs were characterized by dynamic light scattering, UV-visible (UV-Vis) spectroscopy and scanning electron microscopy. These AgNPs were evaluated for antimicrobial activity and photocatalytic dye degradation. The AgNPs showed antibacterial activity against and with 6 mm, 5 mm and 8 mm zone of inhibition, respectively. Our work also focused on methylene blue degradation in aqueous solution using AgNPs as catalyst which shows 65% of dye degradation. An absorbance peak of 427-437 nm was observed using UV-Vis spectrophotometer. Our study proves that the AgNPs show potent antimicrobial activity against pathogenic bacteria. At room temperature, AgNPs possess rapid, effective and steady catalytic activity in cationic organic dye degradation. The high catalytic activity of AgNPs can be employed in industries and water purification. Our study confirmed that green-synthesized AgNPs are eco-friendly and non-toxic.