AbstractConjugated polymers (CPs) have recently gained increasing attention as photocatalysts for sunlight‐driven hydrogen evolution. However, they suffer from insufficient electron output sites and poor solubility in organic solvents, severely limiting their photocatalytic performance and applicability. Herein, solution‐processable all–acceptor (A₁–A₂)‐type CPs based on sulfide‐oxidized ladder‐type heteroarene are synthesized. A₁–A₂‐type CPs showed upsurging efficiency improvements by two to three orders of magnitude, compared to their donor–acceptor ‐type CP counterparts. Furthermore, by seawater splitting, PBDTTTSOS exhibited an apparent quantum yield of 18.9% to 14.8% at 500 to 550 nm. More importantly, PBDTTTSOS achieved an excellent hydrogen evolution rate of 35.7 mmol h⁻¹ g⁻¹ and 150.7 mmol h⁻¹ m⁻² in the thin‐film state, which is among the highest efficiencies in thin film polymer photocatalysts to date. This work provides a novel strategy for designing polymer photocatalysts with high efficiency and broad applicability.