Nitrogen-doped and undoped titanium dioxide nanoparticles were successfully fabricated by simple chemical method and characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and transmission electron microscopy (TEM) techniques. The reduction in crystalline size of TiO2 nanoparticles (from 20&ndash / 25 nm to 10&ndash / 15 nm) was observed by TEM after doping with N. Antibacterial, antifungal, antioxidant, antidiabetic, protein kinase inhibition and cytotoxic properties were assessed in vitro to compare the therapeutic potential of both kinds of TiO2 nanoparticles. All biological activities depicted significant enhancement as a result of addition of N as doping agent to TiO2 nanoparticles. Klebsiella pneumoniae has been illuminated to be the most susceptible bacterial strain out of various Gram-positive and Gram-negative isolates of bacteria used in this study. Good fungicidal activity has been revealed against Aspergillus flavus. 38.2% of antidiabetic activity and 80% of cytotoxicity has been elucidated by N-doped TiO2 nanoparticles towards alpha-amylase enzyme and Artemia salina (brine shrimps), respectively. Moreover, notable protein kinase inhibition against Streptomyces and antioxidant effect including reducing power and % inhibition of DPPH has been demonstrated. This investigation unveils the more effective nature of N-doped TiO2 nanoparticles in comparison to undoped TiO2 nanoparticles indicated by various biological tests. Hence, N-doped TiO2 nanoparticles have more potential to be employed in biomedicine for the cure of numerous infections.