Recently, it has been established that bacteria are quickly developing resistance to traditional antibiotics; as a result, one of the most significant challenges facing the healthcare sector is treating illnesses linked to bacterial infections. In this work, we used a simple wet chemical approach to easily prepare pure TiO₂ and Eu-doped TiO₂ quantum dots (QDs) with different hexamethylenetetramine (HMT) concentrations: 0.1, 0.15, and 0.2 M. As indicated by XRD results, the pure TiO₂ possesses the tetragonal anatase phase, while the Eu-doped TiO₂ samples prepared with the support of HMT content during sample synthesis promotes the amorphous phase. The Eu-doped TiO₂ sample prepared at 0.1 M HMT has an almost uniform distribution of ultra-fine QDs, with an average particle size distribution of 2.05 ± 0.17 nm, according to the TEM image. The Eu 3d core level doublet at 1134.29 and 1164.21 eV, which correspond to Eu³⁺3d_5/2 and Eu³⁺3d_3/2, respectively, is displayed in the XPS data for the sample prepared at 0.1 M HMT. Based on the findings of the Tauc plot, the sample prepared at 0.2 M HMT is found to have a larger optical band gap than the pure TiO₂ and Eu-doped TiO₂ samples prepared at different HMTA concentrations. According to antibacterial tests, the zone of inhibition for E. coli increases from 7 ± 0.55 to 12 ± 0.60 when the concentration of the Eu-doped TiO₂ sample prepared at 0.15 M HMT is increased from 100 to 300 µg/mL. In the field of biomedical application, this enhanced antibacterial activity of Eu-doped TiO₂ QDs can be utilized to create a potent medication for bacterial resistance.