In this study, we employed the DFT+U method to systematically explore the electronic, and magnetic properties of nickel oxide doped with alkali metal atoms (Li, Na, K). The Hubbard potential-U was judiciously applied to all doped compound resulting from alkali doping, and were found to exhibited half-metallic properties. A noteworthy observation was the half-metallic band gap in the spin-down channel, which exhibited a linear variation with the increasing value of the Hubbard potential. Furthermore, the total magnetic moment was discernible in the supercells, with all supercells demonstrating 100% spin polarization at the Fermi level. Consequently, the findings from this study hold significant potential for applications in spintronics, thereby paving the way for future research in this domain.