<p>In the present work, we experimentally discussed the surface vacancy defect related luminescence and magnetic properties for pure and RE³⁺ ions (Eu³⁺, Gd³⁺) doped NiO nanoparticles synthesized by sol–gel method. In this regard, structural and morphological analyses were carried out by XRD, SEM and TEM measurements to analyze the crystallite size and morphology of prepared nanoparticles, respectively. The compositional analysis was also carried out by the FTIR spectroscopy. The UV visible absorption spectra of all the prepared materials reveal a strong absorption edge in between 300–400&#xa0;nm due to the exciton transition and the optical bandgap energy (E_g) increases with the incorporations of Eu³⁺ and Gd³⁺ ions. On the other hand, the deconvoluted PL spectra for all the prepared samples demonstrate a remarkable blue emission under the excitation wavelength 270&#xa0;nm. The blue emission was attributed to the deep level emission due to intrinsic defect (doubly ionized Ni vacancy) states in prepared doped NiO nanoparticles as supported by CIE1961 chromaticity diagram. In addition, the color purity for the blue emission was also calculated with the help of CIE coordinates and observed a higher value for the doped samples over the pure NiO sample. In continuation, magnetic measurement shows a weak room temperature ferromagnetism in all the prepared nanoparticles. The apperance of weak ferromagnetism due to the presence of induced Ni vacancies on the surface of nanoparticles as confirmed by the PL analysis. Consequently, by the incorporation of RE³⁺ ions (Eu³⁺ and Gd³⁺) in NiO lattice, one can tune the luminescence and magnetization induced by intrinsic defects which can be utilized in the applications of optoelectronic and spintronic devices.</p>