This paper reports the synthesis of bare TiO₂ and various molar concentrations of ruthenium (Ru)-doped TiO₂ nanoparticles by the precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), N₂ adsorption/desorption techniques, X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), Raman spectroscopy, photoluminescence spectroscopy (PL), and electrochemical measurements. The results from the UV-vis spectroscopy clearly indicated a red-shift of the optical response toward the visible region owing to the reduced band gap energy, thus showing an enhancement of the absorption in the visible spectrum. The XRD study showed that the samples were crystallized with the photoactive anatase phase of TiO₂. The microstructural study using Raman spectroscopy indicated that the Ru dopant occupied the substitutional sites in the TiO₂ lattice. According to the Mott–Schottky analysis, the flat band potential of the Ru-doped TiO₂ was shifted to the negative potential. The photocurrent, electrochemical impedance spectroscopy, and photoluminescence revealed a higher photogenerated charge-carriers separation efficiency of the doped sample. The photocatalytic activities of the bare TiO₂ and (0.05–0.2 mol%) Ru-doped TiO₂ nanoparticles were examined by studying the hydrogen production from water using methanol as a sacrificial reagent and Pt nanoparticles as a cocatalyst under light of λ ≥ 320. The optimal iron content was determined to be 0.1 mol% and the corresponding hydrogen production rate was 3400 μmol h⁻¹ in aqueous methanol, which is enhanced by more than 2 times compared to bare TiO₂ (1500 μmol h⁻¹) under the same reaction conditions. The higher activity for the doped materials was attributed to the presence of the Ru dopant to facilitate the visible-light-driven activity by introducing the electron donor/acceptor level of ruthenium and the mid-band energy level of defects between the conduction band minimum and valence band maximum of TiO₂.