<p>The increasing demand for high-performance nanomaterials has stimulated extensive exploration of innovative and sustainable synthesis strategies. In this study, honey is utilized as a natural reducing and capping agent to fabricate block-like stacked copper oxide (CuOBS) structures through a facile and scalable approach, enabling controlled morphology and enhanced electrochemical functionality. This bio-inspired synthesis eliminates the need for energy-intensive conditions and dangerous chemicals, which is consistent with the concepts of green chemistry and sustainable development. The resulting CuOBS material exhibits excellent surface activity, nanoscale uniformity, and structural integrity. FE-SEM analysis clearly shows that the material is having a morphology of block-like stacked structures. The average surface area of the synthesized metal oxide is found to be 67.8 m²g^− 1. To evaluate their performance across key application domains, two important areas, energy storage and electrochemical detection of serotonin, a vital neurotransmitter, were systematically investigated. When used as an electrode in supercapacitor designs, the material exhibits excellent rate capability, good electrochemical stability, and a high C_<i>s</i>p, with a maximum value of 822.4 Fg^− 1 at a scan rate of 10 mVs^− 1. The material’s high sensitivity, selectivity, and low detection limit as a serotonin sensor, which can detect up to 50 nM, highlight its potential in biological diagnostics. The versatile performance of the synthesized CuOBS highlights its potential for advanced energy storage and biomedical applications.</p>