© 2022 Elsevier B.V.The irradiation induced effects on structural, morphological and luminescence characteristics of Nb:TiO2 phosphors were systematically investigated. Possible defect centers present in the Nb:TiO2 phosphors were also characterized. Anatase phase of TiO2 with minor parasitic Nb-containing phases was specified in crystallographic structure of phosphors. Crystalline size and internal stress enhance with enhancing the exposed dose. The observed rise in the crystalline size was also confirmed in morphological evolution. Moreover, the Nb:TiO2 phosphor exhibits five different photoluminescence peaks. Intensity variations and blue-green–red shifts on the PL peaks were observed after irradiation exposures. Similarly, various trap sites/centers with depth energies between 1.09 eV and 1.99 eV were found in the thermoluminescence analysis. The irradiation exposures both enhance the oxygen vacancies and cation interstitial defects in the structure. The results have depicted that gamma exposure significantly affects the crystallographic and luminescence features of the Nb:TiO2 nanophosphors.