Polymeric photocatalysts are promising for solar-driven hydrogen production but are often limited in aqueous environments by aggregation-induced exciton recombination and inefficient charge extraction. Here, a dual electron-acceptor polymer photocatalyst, PBT, was designed to enhance electron-withdrawing ability and proton reduction; however, aggregation still restricted hydrogen evolution. To overcome this limitation, fluorine and ethylene glycol substituents were introduced to improve backbone planarity and hydrophilicity, optimizing electronic structure and polymer–water interfacial properties. As a result, charge separation and electron extraction were enhanced, and the optimized polymer, 4EG-PBTz-F, achieved a high hydrogen evolution rate of 3.095 mmol g⁻¹ h⁻¹, demonstrating that combined electronic and interfacial control is an effective design strategy for high-performance polymer photocatalysts.