AbstractDeveloping low‐cost, high‐performance, and durable photoanodes is essential in solar‐driven photoelectrochemical (PEC) energy conversion. Sb₂S₃ is a low‐bandgap (≈1.7 eV) n‐type semiconductor with a maximum theoretical solar conversion efficiency of ≈28% for PEC water splitting. However, bulk Sb₂S₃ exhibits opaque characteristics and suffers from severe photocorrosion, and thus the use of Sb₂S₃ as a photoanode material remains underexploited. This study describes the design and fabrication of a transparent Sb₂S₃‐based photoanode by conformably depositing a thin layer of conjugated polycarbazole frameworks (CPF‐TCzB) onto the Sb₂S₃ film. This structural design creates a type‐II heterojunction between the CPF‐TCzB and the Sb₂S₃ with a suitable band‐edge energy offset, thereby, greatly enhancing the charge separation efficiency. The CPF‐TCzB/Sb₂S₃ hybrid photoanode exhibits a remarkable photocurrent density of 10.1 mA cm⁻² at 1.23 V vs reversible hydrogen electrode. Moreover, the thin CPF‐TCzB overlayer effectively inhibits photocorrosion of the Sb₂S₃ and enables long‐term operation for at least 100 h with ≈10% loss in photocurrent density. Furthermore, a standalone unbiased PEC tandem device comprising a CPF‐TCzB/Sb₂S₃ photoanode and a back‐illuminated Si photocathode can achieve a record solar‐to‐hydrogen conversion efficiency of 5.21%, representing the most efficient PEC water splitting device of its kind.