Carbon dioxide (CO₂) extent in the atmosphere has gradually increased because of excessive activities such as burning fossil fuels and deforestation. Converting CO₂ into value-added hydrocarbon fuels over semiconductors by using solar energy is thus essential to reduce the greenhouse effect. In this study, novel hierarchical graphene–Zn_0.5Cd_0.5S (xG-ZCS) nanocomposites were constructed through a straight forward dual-step hydrothermal approach at 180 °C. The prepared composites exhibited enhanced visible-light photocatalytic transformation of CO₂ to methanol (CH₃OH). The 2G-ZCS (2 wt% graphene-Zn_0.5Cd_0.5S) composite produced the highest amount of CH₃OH (approximately 1.96 μmol g⁻¹ h⁻¹), that is almost 98 times greater than pure ZCS nanospheres (Zn_0.5Cd_0.5S). The increased photocatalytic CO₂ reduction could be as a result of graphene, which served as an exceptional electron receiver and carrier, sinking the reconsolidation of charge mobility and enhance the catalytic property. The electrochemical impedance spectroscopy and transient photocurrent analysis was analyzed to demonstrate the proposed photocatalysis mechanism.