In this paper, we report the enhanced photocatalytic activity and antibacterial ability of nickel oxide (NiO) nanostructures synthesized by the facile solution combustion route using nickel nitrate as an oxidizer and starch and malic acid as a fuel. The tests of powder X-ray diffraction (XRD) and High-resolution transmission electron microscopy (HRTEM) indicated that the NiO nanostructures are possessing cubic crystal structure and the growth of sheets-like morphologies. Besides, the optical studies provided that the NiO nanostructures are exhibiting well-defined absorption peaks in the UV region, i.e., the blue shift from the absorption edge of bulk NiO. Also, the tests of antibacterial activity with the help of various bacterial strains, Klebsiella pneumonia, Acinetobacterbaumannii, Pseudomonas aeruginosa, Citrobacter freundii, Escherichia coli, Vibrio cholerae were performed. The results proved that the NiO nanostructures are inhibiting bacterial cell growth significantly through the cell membrane distraction and associated breakdown of cell enzymes, where all these mechanisms are supporting the enhanced antibacterial activity. Further tests confirmed for the NiO nanostructures photocatalytic activity as a means of degrading the methyl orange (MO) dye under visible light irradiation.