Nanocomposites composed of one-dimensional (1D) CdS nanowires (NWs) and transition metal chalcogenide (such as NiS or MoS₂) have been fabricated through a two-step solvothermal process. The as-prepared nanocomposites were characterized using a combination of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) method, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence (PL) and photoelectrochemical (PEC) techniques. The properties of the nanocomposites strongly depend on the amount of transition metal chalcogenide. Compared with pristine CdS NWs, the optimal amount of transition metal chalcogenide results in enhanced photoelectrochemical (PEC) and photocatalytic activities for hydrogen evolution reaction (HER) in the presence of sacrificial agents. The enhanced PEC and HER activities are attributed to the intimate contact between CdS and transition metal chalcogenide that efficiently enhances charge carrier separation. To gain deeper insight into the mechanism behind the enhanced performance, ultrafast dynamics studies based on femtosecond transient absorption (TA) techniques have been applied to probe the charge carrier dynamics. The optimized nanocomposite showed higher average charge carrier lifetime than that of pure CdS NWs, potentially leading to more efficient charge separation and transfer. The dynamics results agree well with the photocatalytic results in that the longer charge carrier lifetime seems to correlate with improved performance in hydrogen evolution. This work demonstrates a facile approach to controlled synthesis of nanocomposites with well-defined structures for improved PEC and photocatalytic applications, particularly involving the use of biomass for HER from water splitting.