In this work, we have prepared Co‐doped ZnO nanocomposites by zinc nitrate and cobalt sulfate as new precursors via the coprecipitation method and the samples were followed to identify the morphological, optical, structural, and magnetic properties. The XRD patterns revealed the crystalline nature of nanoparticles with hexagonal wurtzite structures, which meant that Co impurity did not disturb the structure of pure ZnO and the minimum crystallite size of nanoparticles was calculated to be around 37 nm. The XRD patterns also showed the lattice parameter increase owing to the incorporation of a Co dopant. The TEM results revealed the sphere‐like particles whose size varied between 56 and 88 nm in diameter at a 4% level of impurity. DRS analysis identified that the band gap energy decreased from 3.18 eV for the pure substance to 2.36 eV for the 10% impure substance. VSM analysis exhibited that the saturation magnetization value increased to 8.4 × 10−3 emu/g for the highest Co content of 10%, which indicated the ferromagnetic behavior of NPs.