Abstract: | In the present study, silver nanoparticles (AgNPs) were synthesised by adding 1 mM Ag nitrate solution to different concentrations (1%, 2.5%, 5%) of branch extracts of Eurycoma longifolia, a well known medicinal plant in South–East Asian countries. Characterisation of AgNPs was carried out using techniques such as ultraviolet–visible spectrophotometry, X‐ray diffractrometry, Fourier transform infrared–attenuated total reflection spectroscopy (FTIR–ATR), scanning electron microscopy. XRD analysis revealed face centre cubic structure of AgNPs and FTIR–ATR showed that primary and secondary amide groups in combination with the protein molecules present in the branch extract were responsible for the reduction and stabilisation of AgNPs. Furthermore, antioxidant [2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐Azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid)], antimicrobial and anticancer activities of AgNPs were investigated. The highest bactericidal activity of these biogenic AgNPs was found against Escherichia coli with zone inhibition of 11 mm. AgNPs exhibited significant anticancer activity against human glioma cells (DBTRG and U87) and human breast adenocarcinoma cells (MCF‐7 and MDA‐MB‐231) with IC50 values of 33, 42, 60 and 38 µg/ml.Inspec keywords: biomimetics, cancer, antibacterial activity, nanoparticles, silver, microorganisms, cellular biophysics, biomedical materials, nanomedicine, nanofabrication, X‐ray diffraction, Fourier transform infrared spectra, attenuated total reflection, ultraviolet spectra, visible spectra, proteins, molecular biophysics, biochemistryOther keywords: Biomimetic synthesis, anticancer activity, Eurycoma longifolia branch extract‐mediated silver nanoparticles, nitrate solution, medicinal plant, ultraviolet‐visible spectrophotometry, X‐ray diffractometry, Fourier transform infrared‐attenuated total reflection spectroscopy, FTIR‐ATR spectroscopy, scanning electron microscopy, XRD, face centre cubic structure, primary amide groups, secondary amide groups, protein molecules, antioxidant, 2,2‐diphenyl‐1‐picrylhydrazyl, 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid), antimicrobial activity, bactericidal activity, biogenic silver nanoparticles, Escherichia coli, zone inhibition, DBTRG human glioma cells, U87 human glioma cells, MCF‐7 human breast adenocarcinoma cells, MDA‐MB‐231 human breast adenocarcinoma cells, Ag |