The replacement of expensive noble-metals cocatalysts with inexpensive, earth-abundant, metallic nonmetal materials in most semiconductor-based photocatalytic systems is highly desirable. Herein, we report the fabrication of stable 1T-MoS2 slabs insitu grown on CdS nanorods (namely, 1T-MoS2@CdS) by using a solvothermal method. As demonstrated by ultrafast transient absorption spectroscopy, in combination with steady-state and time-resolved photoluminescence, the synergistic effects resulting from formation of the intimate nanojunction between the interfaces and effective electron transport in the metallic phase of 1T-MoS2 largely contribute to boosting the photocatalytic activity of CdS. Notably, the heterostructure with an optimum loading of 0.2wt% 1T-MoS2 exhibits an almost 39-fold enhancement in the photocatalytic activity relative to that exhibited by bare CdS. This work represents a step towards the insitu realization of a 1T-phase MoS2-based heterostructure as a promising cocatalyst with high performance and low cost.