Renewable and environmentally benign hydrophilic carbon quantum dots (CQDs) were synthesized using a hydrothermal method. Subsequently, composite membranes of Nafion/CQDs, demonstrating outstanding performance metrics for vanadium redox flow batteries (VRFBs), were developed. Employing a straightforward solution-casting technique, these membranes exhibited superior proton conductivity and reduced vanadium ion permeability. Tested at an elevated current density of 120 mA/cm2, the single cell VRFB integrated with the optimized Nafion/CQDs composite membrane outperformed its commercial counterparts, achieving a high coulombic efficiency of approximately 96.13 % and an energy efficiency of nearly 85.46 %. Moreover, it demonstrated significant cycle life, retaining about 17.1 % of its capacity after 100 cycles, compared to 27.2 % capacity retention for the N-recast membrane over the same period. These results position the Nafion/CQDs composite membrane as a formidable contender in the VRFB domain, emphasizing its potential for broader commercial applications.