Mn₃O₄ nanoparticles (NPs) find a broad range of applications in catalysts, energy storage devices, wastewater remediation, biosensors, photocatalysts, medical/antimicrobial agents, and in controlling drug-resistant pathogens. In the present work, Mn₃O₄ NPs were successfully produced by using a simple, cheap, and plant-mediated green synthetic route. The leaf extract of Coriandrum sativum was treated with MnNO₃.6H₂O at 60°C and pH 12 to produce Mn₃O₄ NPs. The synthesized NPs were characterized by XRD, FTIR SEM, and UV-Visible analyses. Their electrochemical properties were investigated by cyclic voltammetry (CV) and they were also subjected to antibacterial evaluation studies by the disc diffusion method. The XRD analysis revealed the tetragonal structures of Mn₃O₄ NPs with a crystallite size of 23.62 nm. FTIR spectroscopy displayed the Mn-O vibrations at 730 cm^-1. SEM analysis verified the aggregated and flake-like morphology of Mn₃O₄ NPs. UV-Visible spectroscopy revealed the absorption peaks at 232 and 360 nm, which correspond to the permissible charge transfer transitions of O^2-→Mn²⁺ and O^2-→Mn³⁺, respectively. The CV curves clearly indicated the redox reactions and the reversible behavior of Mn₃O₄ NPs. The antibacterial activity of Mn₃O₄ NPs against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) was also evaluated using ciprofloxacin as a standard reference drug.