The development of efficient, stable, and scalable photocathodes is a central challenge in the advancement of solar-driven hydrogen production. Antimony trisulfide (Sb₂S₃) has emerged as a highly attractive candidate due to its earth abundance, suitable bandgap (~1.7 eV), high absorption coefficient, and intrinsic photostability. However, its application as a photocathode is hindered by intrinsic bulk defects, non-radiative recombination, inherently poor electron–hole separation, and instability in aqueous environments, leading to low photocurrent densities and limited operational lifetimes. In this work, we report a systematic study on the structural improvement and interfacial engineering of Sb₂S₃-based photocathodes, fabricated via thermal evaporation, to enhance their performance for photoelectrochemical (PEC) hydrogen generation. We systematically explored a wide range of annealing temperatures and seed layers to optimize the preferred orientation, thereby enhancing charge transport. In addition, various electron and hole transport layers were investigated to improve charge extraction and achieve better band alignment with Sb₂S₃. Notably, the incorporation of zinc oxysulfate (ZnOS) facilitated favorable band bending at the Sb₂S₃ interface, which significantly enhanced charge transport. Material and interface characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and steady-state photoluminescence (PL) spectroscopy. XRD confirmed the orthorhombic phase of Sb₂S₃ with high crystallinity and preferred orientation in hk1, while SEM revealed uniform film morphology with no visible pinholes or large-scale defects. PL quenching observed in the presence of ZnOS provided evidence of enhanced interfacial charge transfer and reduced recombination rates. The optimized device architecture, evaluated in a three-electrode PEC configuration, delivered a photocurrent density nearly an order of magnitude higher than that of bare Sb₂S₃ at −0.3 V vs. RHE under standard AM 1.5G illumination. Furthermore, stability testing in a neutral aqueous electrolyte (pH ~7) confirmed the robustness of the interfacial design and the chemical durability of the photoelectrode stack. These findings demonstrate that interfacial and catalytic optimization can unlock the full potential of Sb₂S₃ photocathodes, offering a scalable pathway toward efficient and durable chalcogenide-based systems for solar fuel generation.