Summary Cadmium sulfide (CdS) is one of the most famous photocatalyst for water splitting because of relevant band edge position. But it has disadvantage such as recombination of charge carrier and photocorrosion in pure water that sacrificial materials must be used to fix it. On the other hand, the use of other photocatalysts alongside it can greatly eliminate these disadvantages. So, in favor of boosting photocatalytic efficiency, it was coupled with BiFeO3 that is a promising visible light active perovskite structure and has ferroelectric properties. The CdS and BiFeO3 powders were synthesized by precipitation and hydrothermal methods, respectively. The pure samples and heterojunctions were investigated by XRD, FESEM, transmission electron microscopy, EDX, UV‐vis, PL, N2 adsorption/desorption isotherms, photocurrent density measurement, electrochemical impedance spectroscopy and Mott‐Schottky analysis to compare the structure, composition, morphology, and optical property before and after modification. The maximum photocatalytic activity, 600.2 μmol/g/h was obtained by heterojunction containing 50 wt% BiFeO3 (CB‐50) from pure water. Also from the experiments results, CB‐50 showed much higher reusability than pure CdS. The enhanced stability and photocatalytic activity of CB‐50 are mainly attributed to charge separation as a result of Z‐scheme charge transfer mechanism as well as the increased light absorption efficiency. In addition to increasing hydrogen production, the ability to use pure water in a closed system without additional materials is other advantage of this photocatalyst.