Microalgae are a valuable source of renewable biomass that contains lipids, proteins, and bioactive compounds. It is a promising sustainable candidate for green synthesis of nanomaterials (NMs). The present work announces a novel biogenic approach for synthesis of platinum nanoparticles (Pt NPs) employing Tetradesmus obliquus (green microalgae) as a green reducer and surfactant. This is revolutionary breakthrough in the field of bionanotechnology by employing a unique, cheaper, biocompatible, and non-toxic method for the production of Pt NPs. This investigation consists of isolating and purifying algae in a flask with incorporating a metal precursor into the microalgae culture. As-synthesized Pt NPs were examined by various spectroscopic techniques viz. XRD, EDS, FTIR, DLS, SEM and TEM to confirm its phase, crystallinity, purity, shape, and size. The XRD pattern revealed crystal structure of Pt NPs with crystallite sizes 26.75 nm, while TEM discloses spherical shape with particles sizes around 21.25 nm-31.50 nm. The zeta potential value of algae-mediated Pt NPs found to be -15.8 mV which suggested higher stability of synthesized NPs. Before an antibacterial evaluation of biosynthesized Pt NPs, its molecular docking was assessed by taking suitable amino acid. Further, executed an antibacterial activity of biosynthesized NPs against gram-positive and gram-negative bacteria. With its affordability and eco-friendly attributes, it sets a new standard technique in NPs fabrication.