Carbon doped titanium oxide (CTiO2) photocatalyst was successfully synthesized by the sol–gel method. The crystal structure, surface morphology, and optical properties of CTiO2 have been characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area (SBET), scanning electron microscope, UV–Vis, X-ray spectroscopy (EDS), Fourier transform infrared and X-ray photoelectron spectroscopy. The photocatalytic degradation of acetaminophen (AMP) in aqueous solution, seawater, and polluted seawater has been investigated by using the synthesized photocatalyst under irradiation of UV and natural sunlight. The effectiveness of CTiO2 compared to pure TiO2 toward the photocatalytic removal of AMP was significantly observed. The optimized conditions including catalyst dose, initial concentration of AMP and solution pH were also studied for effective photocatalytic removal. The highest degradation rate was obtained when 2.0 g L−1 of the catalyst was used at pH 7. The kinetic results revealed that the photocatalytic degradation of AMP using CTiO2 obeyed a pseudo-first-order reaction kinetics.