This research introduces a method for power management in hybrid fuel cell-based electric vehicles (HFCBVs) using adaptive super-twisting sliding mode control with dynamic gain (ASTSMC-DG). This enhances efficiency and reliability in energy conversion systems, particularly in bi-directional power converters (BD-PCs) and integrated backup storage systems (IBSSs). The ASTSMC-DG minimises chattering and slow error convergence typically associated with traditional sliding mode control. Simulations show an 8.56% increase in regenerative energy recovery over the PI controller, extending battery life and improving energy efficiency in EVs. The system exhibits lower voltage, current, and torque fluctuations than PI control, with a fuel cell utilisation ratio of 61.2% compared to 72.5% in PI control. This indicates effective power distribution among resources, thereby improving the balance of energy management. A sensitivity analysis confirms the proposed control strategy’s robustness, maintaining efficient energy recovery at approximately 570–760 kJ.