Defects and doping play an important role in determine the physical and/or chemical properties of semiconductor materials. In this study, thermoelectric performance of nickel doped zinc oxide (Ni doped ZnO) was investigated in order to obtain the optimal defects concentration. The Ni doped ZnO thin films were prepared using thermal co-evaporation technique. It is observed that all the obtained samples exhibited preferential orientation along (002), the increases of Ni contents leads to crystallinity enhancement and lower surface roughness. The morphological, compositional and topological results of the Ni doped ZnO thin films indicate that the increases of Ni contents to 0.91% leads to low surface roughness (5.4 nm). The samples demonstrated an electrons concentration of 1.5 × 1019 cm− 3 , Seebeck coefficient at 178 μV∙K− 1 and an electrical conductivity of 3175 S∙m with a maximum power factor of 101 μW∙m− 1 K− 2 . The doping technique used in this work, showed promising results in producing high thermoelectric performance.