In the present contribution, we demonstrate that the sluggish kinetics of oxygen evolution reaction (OER) over the bismuth sulfide (Bi₂S₃) photoanode, which severely restricts its photoelectrochemical activity, is markedly accelerated by employing a sulfate-containing electrolyte. First-principle calculation points to the spontaneous adsorption of sulfate (SO₄²⁻) on Bi₂S₃ and its capacity of stabilizing the OER intermediates through hydrogen bonding, which is further reinforced by increasing the local density of states near the Fermi level of Bi₂S₃. Meanwhile, the electron transfer is also promoted to synergistically render the rate-determining step (from O* to OOH*) of OER over Bi₂S₃ kinetically facile. Last but not least, benefitting from such enhanced OER activity and efficient charge separation resulted from depositing Bi₂S₃ on the zinc oxide nanorods (ZnO NRs), forming a core–shell heterojunction, its photocurrent density achieves 8.61 mA·cm⁻² at 1.23 V_RHE, far surpassing those reported for additional Bi₂S₃-based and several state-of-the-art photoanodes in the literature and further exceeding their theoretical limit. The great promise of the Bi₂S₃/ZnO NRs is in view of such outperformance, the superior Faradaic yield of oxygen of more than ~ 80% and the outstanding half-cell applied bias photon-to-current efficiency of ~ 1% well corroborated.