© 2022, King Abdulaziz City for Science and Technology.Organic@inorganic hybrid nanoflowers (hNFs), which are widely used in enzyme purification and catalytic activity applications, include both organic and inorganic components. In this study, hNFs were synthesized with the combination of Ascoseira mirabilis extract and Cu in phosphate-buffered saline (PBS) while altering the concentration and medium pH instead of using expensive molecules that are difficult to obtain such as enzymes or DNA. According to the obtained FE-SEM images, the morphology of the hNFs was related to the pH of the PBS (synthesis did not occur at pH 5) and the volume of the extract. The presence of Cu and other components was detailed with EDX mapping. The presence of functional groups playing key roles in the synthesis process was evaluated based on FT-IR peaks. The Cu hNFs exhibited peroxidase-like catalytic activity against guaiacol and demonstrated antimicrobial and antioxidant activities. This study is original and innovative in terms of using an Ascoseira mirabilis extract for hNF synthesis and evaluating the antioxidant, catalytic, and antimicrobial activities of Ascoseira mirabilis-based hNFs. The research sheds light on hNF synthesis and the possibility of biological activity application studies performed with bioextracts instead of biomolecules obtained via expensive and complex processes.