Owing to a wide range of potential applications of noble metal nanoparticles such as palladium nanoparticles (PdNPs) and platinum nanoparticles (PtNPs), their simpler and eco-friendly synthesis has attracted the scientific community worldwide. This study demonstrates bacterium Pseudomonas stutzeri mediated simple, eco-friendly and optimized green method for the biogenic synthesis of PdNPs and PtNPs. The synthesis methods were optimized by studying the effects of variations in the parameters namely concentration of precursors, pH, temperature and reaction time. The biogenic PdNPs and PtNPs were then characterized and confirmed by using various spectroscopic and imaging techniques. Further, investigation of catalytic activity of PdNPs to reduce 4-nitro phenol (4-NP) into 4-amino phenol (4-AP) indicated the excellent activity and the reaction was found to follow pseudo first-order kinetics. The study of the effects of variation in catalytic reaction parameters namely concentration of 4-NP, catalyst dosage, and pH demonstrated the highest of 98.14% reduction in a reaction containing 10 ppm 4-NP, 0.3 mg of catalyst in 30 min. In addition, the biogenic PtNPs of the present study showed antihaemolytic activity and haemocompatibility. Furthermore, the test of antioxidant activity of PtNPs showed good 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity.