A nickel oxide nanoparticle (NiO NP) composite with carbon dots (C‐dots), (NiO NPs@C‐dots) was synthesized, characterized, and then its antibacterial activity was evaluated. NiO NPs were prepared using Buddleja polystachya Fresen leaf extract and Ni(NO3)2.6H2O as precursors. The C‐dots were synthesized from benzene‐1,4‐diamine and citric acid. The cubic structure of the NiO NPs and NiO NPs@C‐dots was in phase with their average particle size distributions of 21.47 ± 0.56 and 21.61 ± 0.34 nm, respectively. The surface morphology of the NiO NPs@C‐dots was characterized using field emission scanning electron microscopy and also revealed a large surface area, which is advantageous for the specified application. The X‐ray diffraction result indicated a cubic face wurtzite structure and the crystalline nature of the NiO NPs. Carbon‐doped compounds had no influence on the crystal structure of the NiO compound and no new peaks were observed. The antibacterial activity of a composite made up of NiO NPs@C‐dots was tested, as well as the antibacterial activities of compounds produced against human photogenic bacterial strains. Both NiO NPs and NiO NPs@C‐dots were found to be powerful against all bacterial strains, based on the bioassay results. NiO NPs and NiO@C‐dots appeared to display strong to inhibitory effects of 14–20 mm and 17–23 mm, respectively. [ABSTRACT FROM AUTHOR]