Catalytic hydrogenation of CO₂ to hydrocarbons has received considerable attention due to its potential for enhancing environmental sustainability. Although the research on the activity enhancement reached a matured level, achieving systematic selectivity control of CO₂-derived hydrocarbons is still a formidable challenge. Herein, we developed a catalytic route for control of hydrocarbon selectivity utilizing hydrogen spillover phenomena using potassium-promoted iron-based catalysts supported on CuAl₂O₄ spinel oxides (denoted as FeK/CAO) with systematically modified surface properties for controlled activations of CO₂ and H₂. Different thermal treatments constructed a series of FeK/CAO catalysts having systematically controlled surface compositions of individual catalytic components with their different dispersions and hence mutual distances, different degrees of reducibility, and different concentrations of oxygen vacancy. The controlled surface characteristics changed H₂ activation process and hence the hydrogen spillover phenomena during CO₂ hydrogenation, resulting in the systematic control of CO₂ conversion and hydrocarbon selectivity. Property–performance relationship proposed that the hydrogen spillover can be influenced by the reducibility, the Cu particle sizes, and the distance between hydrogenation catalytic sites and C–C bond formation catalytic sites. This study successfully demonstrates the ability to control the ratio of olefins to paraffins in the hydrocarbon products derived from CO₂ hydrogenation.