This work focuses on the effect of surface hydrophobicity of SiO₂ supports on the performance of SiO₂-supported Fe catalysts during Fischer–Tropsch synthesis (FTS). Three different hydrophobized SiO₂ supports were synthesized by varying the amount of the dichlorodimethylsilane used for the hydrophobization of the hydrophilic mesoporous SiO₂ gel. Fe metal of approximately 9 wt% was loaded on the hydrophilic SiO₂, and three hydrophobized SiO₂ supports by homogeneous deposition precipitation. The wholly hydrophobized SiO₂ surface improved the catalytic activity of Fe catalysts because the hydrophobized SiO₂ increased the reducibility of the iron oxide and inhibited readsorption of water over the surface of the Fe catalyst, therefore creating more available active sites for the adsorption of CO. Also, hydrophobized SiO₂ decreased the CH₄ selectivity and C₂–C₄ selectivity and increased C₅₊ selectivity of the Fe catalysts due to the promotion of chain growth by the hydrophobized SiO₂. Furthermore, the hydrophobized SiO₂ decreased the CO₂ selectivity of the Fe catalysts because the hydrophobized SiO₂ hindered the readsorption of water over the surface of the Fe catalysts, which leads to the inhibition of water gas shift reaction and subsequently the hindering of the CO₂ formation.