A unique functionalized organosilane (FOSi) is synthesized and prepared as a hybrid organic-inorganic composite membrane (OICM) using short-side-chain perfluorosulfonic acid (SSC-PFSA) at a large scale for vanadium redox flow battery (VRFB). The OICM solution is fabricated by using 75 wt % of SSC-PFSA and 25 wt % of FOSi and cast with the help of Roll to Roll (R2R) film casting equipment. The OICM's proton conductivity and performance are comparable to the Nafion membrane, owing to additional hydrophilic fields in the hybrid membrane. The OICM possesses proton conductivity of 0.13 S/cm and an ion exchange capacity of 1.44 meq/g, even though the water uptake has been lowered than the PFSA owing to better dispersion of FOSi. OICM has a low vanadium permeability (1.52 × 10−6 cm2/min) and remarkable selectivity, which is a significant benefit. Consequently, over 45th cycles, the OICM performs comparably to Nafion in energy efficiency combined with coulombic and voltage efficiency. The unit cell-test with OICM shows a normalized coulombic efficiency due to low permeability than PFSA and high voltage efficiency due to high proton conductivity. Hence OICM divulges a promising path to developing an alternative membrane for energy devices.