Abstract Spherical nanoparticles of zinc oxide (ZnO NPs) were synthesized by an eco-friendly green combustion method using citrate containing Artocarpus gomezianus fruit extract as a fuel. The morphology, compositions and structure of the product were characterized by Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infra-red (FTIR), UV–Visible (UV–Vis) and Raman Spectroscopy. Highly uniform spherical zinc oxide NPs were subjected to cytotoxicity, antifungal and antibacterial activities. PXRD patterns show that the product formed belongs to a hexagonal wurtzite system. SEM micrographs reveal that the particles are agglomerated. The TEM images demonstrate that the particles are highly uniform spherical in shape and loosely agglomerated. Scherrer's method and W H plots were used to calculate the average crystallite sizes, yielding 39, 35, 31 and 40, 37, 32 nm for ZnO NPs prepared with 5, 10 and 15 mL of 10% Artocarpus gomezianus fruit extract, respectively. These results were confirmed by the TEM observations. Breast cancer cell lines (MCF-7) were subjected to in vitro anticancer activity. MTT assay revealed a good anticancer activity of ZnO NPs against MCF-7. Zone of the inhibition method shows that the spherical ZnO NPs also exhibit significant antibacterial activity against staphylococcus aureus and antifungal activity against Aspergillus niger. The synthesized ZnO NPs can find plausible biological applications.