In this study, F/Cu/VZn/Hi multi-defect coupled ZnS systems were innovatively constructed, and the regulatory mechanisms of their structure, magnetism, conductivity type, and photocatalytic CO2 reduction performance were systematically investigated. Structural stability of the systems is significantly enhanced by the synergistic introduction of F/Cu/Hi (formation energy as low as − 4.376 eV). Magnetism of the systems originates from unpaired spin electrons in the Cu2-3d9 orbital, with a magnetic moment contribution of 1 μB. A regular transition of magnetic moment spin distribution from localized states (Cu2+-S2−) to delocalized states (Zn-4s) is observed with increasing F− concentration. Different conductivity types can be achieved via precise regulation of F− concentration (n-type at 4.23% F−, p-type at 1.41%/2.82% F−). The optimized n-type system exhibits a narrow band gap (1.78 eV), broad spectral response (strong absorption in visible-infrared region), low electronic effective mass (0.20 m0), and high average hole-electron effective mass ratio (({bar{text{D}}}) = 3.54). Its conduction band minimum energy level is precisely matched with the potential for CO2 reduction to CH4, and CO2 adsorption/activation efficiency is significantly enhanced by the short-range synergistic effect between VZn and F−. ZnS-based functional materials with tunable magnetism, controllable conductivity type, and high-efficiency photocatalytic performance are successfully constructed, providing new insights and experimental support for the design of high-performance materials for spintronic devices and photocatalytic CO2 reduction cells.