As promising heterojunction photocatalysts, the binary CdS-based heterojunctions were investigated extensively. In most of the reported CdS-based heterojunctions, however, electrons come from the semiconductor with wide band gap (e.g., TiO2) would limit the visible-light absorption of CdS and hence lower the performance. In this work, we introduced 1T-MoS2 to form a novel ternary heterojunction, namely CdS/1T-MoS2/TiO2, in which 1T-MoS2 has more positive conduction band than CdS and TiO2. The hydrogen evolution rate of CdS/1T-MoS2/TiO2 reaches 3.15 mmol g−1 h−1, which is approximately 12 and 35 times higher than that of pure CdS and CdS/TiO2 binary heterojunction under the same conditions, respectively. This performance enhancement could be attributed to the presence of 1T-MoS2 and a plausible mechanism is proposed based on photoelectrochemical characterizations. Our results illustrate that the performance of CdS-based heterojunctions for solar hydrogen evolution can be greatly improved by appropriate materials selection.