Carbon–silica composite is prepared by the impregnation of silica with aqueous glucose solution followed by drying and calcination in an inert atmosphere. This material is proposed as a support for the potassium‐promoted iron catalysts for Fischer–Tropsch synthesis (FTS). The catalysts are prepared by incipient wetness impregnation. The reducibility of CQ‐supported iron is increased and Hägg carbide is formed in the course of activation in CO/H2 flow at 400 °C for 2 h. Subsequent exposure in FTS conditions results in the significant increase of iron carbide particles, from 3–4 to 20–30 nm, while no such increase is detected for the pure silica as support. The carbon–silica composite support provides a beneficial effect on the catalytic activity of iron in CO hydrogenation as well as the suppression of methane formation and increasing Anderson–Schulz–Flory distribution (ASF) chain growth parameter. The catalysts are characterized by nitrogen adsorption, X‐ray absorption spectroscopy (XPS), transmission electron microscopy (TEM), and in situ magnetic measurements in the course of temperature‐programmed reduction by H2 and synthesis gas.