Ni1-xAgxO nanoparticles (NPs) with x = 0.00, 0.02, 0.04, 0.06, and 0.08) were fabricated using the composite hydroxide mediated (CHM) method. The effects of Ag doping on the structural, magnetic, and antimicrobial characteristics of NiO NPs have been reported. The stretching mode of the Ni–O molecules was identified at 443 cm−1 in the Fourier transform infrared spectra. The aggregation of nanoparticles with different sizes and shapes is seen under transmission and scanning electron microscopes. The blocking temperature (TB) peak in zero-field cooled (ZFC) magnetization curves display the magnetization from the core of NPs. This peak is absent for the samples with x=0.00 and 0.02, which show instead a small net magnetization from the antiferromagnetic core of these NPs. However, a TB peak was found for the samples with x=0.04,0.06and0.08, at 22, 72, and 65 K, respectively, which indicates that the magnetization is induced from the AFM core of NiO NPs for higher Ag doping. With an increasing concentration of Ag in the NiO NPs, the net magnetization did increase and a maximum was found for x = 0.04 at 300 K. For a higher doping concentration of 8 % Ag, a sharp decrease in magnetization was observed. Furthermore, the efficacy and synergistic effect of Ag doping had been analyzed for the effective improvement of the antibacterial properties of NiO NPs. Pure and Ag-doped NiO NPs were exploited to assess their anti-microbial activity against Enterobacter sp., E. coli, P. aeruginosa, and S. pyrogens. The study revealed that anti-bacterial or anti-biofouling properties were introduced as an additional attribute to NiO NPs by incorporation of Ag ions due to its inherent nature as an antimicrobial agent and enhanced its capability to sterilize microbial pathogens.