The current study outlines an environmentally friendly procedure to synthesis the extracellular secondary metabolite-mediated copper oxide nanoparticles (CuONPs) using Bioinspired green chemistry method with Pseudomonas aeruginosa isolated from a marine water sample. The in vitro bio-reduction of Copper sulphate to CuONPs in the presence of secondary metabolites was confirmed using various analytical techniques, including UV-visible spectroscopy, FTIR spectroscopy, particle size analysis, scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the UV-visible spectroscopy the synthesised nanoparticles was characterized with the maximum absorbance at 570 nm. SEM analysis showed the nanoparticles to be nearly cuboidal in shape with the size range of 108.0 nm to 252.2 nm at the 1,00,000x magnification. X-ray diffraction revealed particle sizes ranging from 4.19 nm to 26.95 nm with diffraction peaks at 38.05° and 31.67°, corresponding to lattice planes [6.56] and [100], indicating a polycrystalline wurtzite structure. The synthesized CuONPs exhibited significant antimicrobial activity against clinical pathogenic bacteria such as Escherichia coli, Bacillus cereus, Staphylococcus aureus and Proteus mirabilis, as well as fungicidal activity against phytopathogenic fungi including Alternaria solani, Rhizoctonia solani and Colletotrichum capsici. Additionally the photocatalytic activity of the Pseudomonas aeruginosa mediated CuONPs was estimated through the degradation of the triarylmethane dye-malachite Green.