This study focuses on the biosynthesis of copper oxide-titanium dioxide nanocomposites (CuO-TiO<inf>2</inf>NCs) using Senna auriculata (L.). Roxb. plant flower extract to explore their potential biological activities. This investigation was conducted using a comprehensive characterization technique, including UV�Visible spectrum, FT-IR, XRD, FESEM, and HR-TEM analysis. This result confirms the presence of CuO and TiO<inf>2</inf> at 270 nm and 360 nm in the UV�Vis spectra, while FT-IR analysis shows the presence of various major functional groups. The XRD test confirmed that the synthesized CuO-TiO<inf>2</inf>NCs were crystalline in structure. FESEM and HR-TEM studies indicated that the particles had an irregular spherical shape with an average diameter of 12.5 nm. The CuO-TiO<inf>2</inf>NCs demonstrated antioxidant properties, as evidenced by DPPH activity (89.52 ± 1.39 ), ABTS activity (74.36 ± 1.25 ), and H<inf>2</inf>O<inf>2</inf> activity (72.57 ± 1.18 ) at a concentration of 200 μg/mL. CuO-TiO<inf>2</inf>NCs exhibited antibacterial properties against Staphylococcus aureus, with a zone of inhibition of 23.49 ± 0.31 mm at 100 μg/mL, and against Streptococcus pneumoniae, with a zone of inhibition of 20.64 ± 0.32 mm at 100 μg/mL, respectively. When evaluating the anti-cholinesterase activities, the inhibitory effect on AChE activity was 74.82 ± 1.24 at 200 μg/mL, and the effect on BChE activity was 23.68 ± 0.74 at the same concentration. Additionally, the MTT assay on HepG2 cancer cells demonstrated that CuO-TiO<inf>2</inf>NCs exhibited superior anticancer properties. Specifically, at a concentration of 200 μg/mL, the CuO-TiO<inf>2</inf>NCs cells exhibited significantly lower cell viability (27.81 ± 0.95 ). In conclusion, CuO-TiO<inf>2</inf>NCs significantly contribute to antioxidant, antibacterial, and anticancer therapies. © 2025 Elsevier B.V., All rights reserved.