The green method provides stable, rapid, and eco-friendly methods for synthesis nanoparticles with plant extract as capping and reducing agents. This method renders biocompatibility, scalability, and potential medical applications of nanoparticles. This study green synthesized CuO/TiO2 and ZnO/TiO2 nanocomposites using Parkia timoriana bark extract. The synthesized nanocomposites were determined utilizing UV–vis DRS FTIR, XRD, TGA, AFM, FE-SEM, E-DAX, HR-TEM, and XPS. Antioxidant assay and antidiabetic studies revealed the biological activity of nanocomposites. The antioxidant property in ZnO/TiO2 (84.07 %) was higher than in CuO/TiO2 nanocomposites (72.76 %). The IC50 value of CuO/TiO2 and ZnO/TiO2 in α-amylase inhibition assay was 72.12 μg/mL and 75.95 μg/mL, respectively and IC50 value of CuO/TiO2 and ZnO/TiO2 in α-glucosidase inhibition assay was 30.80 μg/ml and 25.69 μg/ml. Thus, it concludes ZnO/TiO2 nanocomposites exhibited higher antioxidant and antidiabetic activity than CuO/TiO2 nanocomposites. These results show that biosynthesized nanocomposites can be used for treating diseases.