Gold nanoparticles (AuNPs) have generated increased interest among diverse metallic nanoparticles because of their unique qualities, which include nano size, low toxicity, comparatively simple fabrication, and precise targeting. Biosynthesis following green method is considered as an advantage when compared to other modes of synthesis. In this present study aqueous stem bark extracts of Eriolaena lushingtonii Dunn. were used for the synthesis of gold nanoparticles. These green-synthesised nanoparticles are characterised by colour change pattern of plant extract from red to purple colour, and the broad peak obtained at 562 nm with UV–vis surface plasmon resonance studies confirm that the synthesised nanoparticles are AuNPs. FT-IR spectroscopic studies confirm that phenols and proteins (amides) of stem bark extract are mainly responsible for capping and stabilisation of synthesised AuNPs. Gold nanoparticles with an average particle size of 55 nm and a zeta potential value of -27 mV, EDAX analysis shows 10.59 weight percentage of Au metal in the sample indicates the purity of sample. SEM imaging, the AuNps are nearly spherical and rough uneven surface. TEM high resolution microscopic studies reveal that the nanoparticles are spherical in shape with sizes ranging from 12 to 15 nm. Synthesised gold nanoparticles are used to assess its antimicrobial and antioxidant properties. AuNPs exhibited antimicrobial property superior to aqueous stem bark extracts. Among the tested pathogens E. coli, Staphylococcus aaureus, Aspergillus flavus are more susceptible microbial organisms. DPPH, hydrogen peroxide and hydroxyl radical scavenging assays AuNPs exhibited good antioxidant properties. The antioxidant potential of stem bark extract and AuNps was observed in a concentration dependent manner. From the results, the green synthesized gold nanoparticles are appropriate and ideal candidates for biomedical applications.