To address the energy needs of the modern world, there is an increasing demand for low-cost energy storage systems with high energy and high power densities. Due to their extraordinary ability to store energy, nanocomposite electrodes have a significant role in supercapacitor applications. The current work describes a simple, one-step hydrothermal synthesis of crystalline BCO nanoflakes (NFs) that is inexpensive and effective for use as a supercapacitor electrode material. The crystal structure and phase formation of BCO material were identified with the help of XRD and FTIR analysis, respectively. FE-SEM analysis is used to confirm that the hierarchical BCO nanoflakes are made of bismuth wrapped around copper. Using a half-cell arrangement and a 6 M KOH electrolyte, the as-fabricated Bi2CuO4 (BCO) nanoflakes-based symmetric supercapacitor displays a specific capacity of 1842 C/g at 3 A/g current density. The trasatti method demonstrates the synergetic charge storage redox behavior of 92.9 % and capacitive behavior of 7.1 %, respectively. The cyclic stability shows an outstanding 88 % capacitance retention over 10,000 cycles in a two-electrode system. The symmetric cell with BCO material exhibits a high specific capacity of 652 C/g at 1 A/g current density with 41 Wh kg−1 energy and power density of 899 W kg−1, respectively. © 2023 Elsevier Ltd