This study explores the structural and optical characteristics of MgO/Ni thin films, along with the impact of annealing. The films, doped with Ni, were deposited on glass substrates using the e-beam evaporation technique. The annealing was done in vacuum at 300 °C for 1 h. The XRD analysis of both as-deposited and annealed thin films revealed diffraction peaks at 2 = 42.1° and 62.3°. These peaks correspond to the (200) and (220) planes of cubic MgO nanostructures, confirming the formation of a well-defined cubic phase. Moreover, annealing improved the crystallinity, indicating enhanced grain growth. UV-Vis absorption spectroscopy revealed a distinct absorption peak occurring between 300 and 350 nm, which is linked to electronic transitions that move valence to conduction band. The bandgap noted to increase from 4.15 eV in the as-deposited films to 4.34 eV post-annealing, reflecting improved crystallinity. Hall measurements highlighted the effect of annealing on charge carrier dynamics and electrical properties, with both as-deposited and annealed films exhibiting n-type conductivity characteristic of MgO-based materials and conductivity increases from 3.65 Ω−1cm−1 to 3.87 Ω−1cm−1 after annealing. Surface morphological images revealed the enhanced surface uniformity in as-deposited as well annealed samples, characterized by smoother and more homogeneous surfaces with fewer defects. The results indicate that annealing plays a crucial role in enhancing the structural and optical properties of Ni-doped MgO thin films. This improvement makes them promising materials for advanced optical, optoelectronic, and electronic applications.