Ion conductive membranes (ICMs) with highly conductive proton selectivity are of significant importance and greatly desired for energy storage devices. However, it is extremely challenging to construct fast proton-selective transport channels in ICMs. Herein, a membrane with highly conductive proton selectivity was fabricated by incorporating porous carbon sieving nanospheres with a hollow structure (HCSNs) in a polymer matrix. Due to the precise ion sieving ability of the microporous carbon shells and the fast proton transport through their accessible internal cavities, this advanced membrane presented a proton conductivity (0.084 S·cm⁻¹) superior to those of a commercial Nafion 212 (N212) membrane (0.033 S·cm⁻¹) and a pure polymer membrane (0.049 S·cm⁻¹). The corresponding proton selectivity of the membrane (6.68 × 10⁵ S·min·cm⁻³) was found to be enhanced by about 5.9-fold and 4.3-fold, respectively, compared with those of the N212 membrane (1.13 × 10⁵ S·min·cm⁻³) and the pure membrane (1.56 × 10⁵ S·min·cm⁻³). Low-field nuclear magnetic resonance (LF-NMR) clearly revealed the fast proton-selective transport channels enabled by the HCSNs in the polymeric membrane. The proposed membrane exhibited an outstanding energy efficiency (EE) of 84% and long-term stability over 1400 cycles with a 0.065% capacity decay per cycle at 120 mA·cm⁻² in a typical vanadium flow battery (VFB) system.