<p>In this work, CeO₂, TiO₂, and CeO₂–TiO₂ nanocomposites were successfully synthesised via a green hydrothermal route using <i>Withania coagulans</i> extract as a bio-reducing and stabilising agent. X-ray diffraction (XRD) confirmed the coexistence of cubic fluorite CeO₂ and anatase TiO₂ phases, whilst HRTEM revealed well-defined lattice fringes corresponding to both metal oxides, indicating strong interfacial contact within the composites. XPS analysis confirmed the successful formation of the CeO₂–TiO₂ heterostructure and revealed the coexistence of Ce³⁺/Ce⁴⁺ and Ti⁴⁺ species. The presence of oxygen vacancies and strong interfacial interactions facilitated charge transfer, contributing to enhanced photocatalytic activity. The CeO₂–TiO₂ (1.5:0.5) nanocomposite exhibited enhanced visible-light absorption and improved surface properties, attributed to synergistic interactions and efficient charge separation. Photocatalytic activity was evaluated against ciprofloxacin (CIP) and methylene blue (MB), where the CeO₂–TiO₂ (1.5:0.5) composite showed the highest degradation efficiencies of 93.17% (CIP) and 96.01% (MB), with superior pseudo-first-order rate constants compared to pure CeO₂ and TiO₂. Reactive oxygen species (⋅OH and O₂⋅⁻) were identified as the dominant contributors to pollutant degradation. The catalyst also demonstrated excellent stability and reusability over five consecutive cycles. These results highlight the potential of green-synthesised CeO₂–TiO₂ nanocomposites as efficient and sustainable photocatalysts for wastewater treatment applications.</p>