<p>In recent decades, crosslinked polymers prepared from silsesquioxane have gained significant attention for their potential applications in textiles. Silsesquioxanes offer significant advantages, including high thermal and chemical stability, environmental compatibility, and tunable functionalization, making them widely studied for various applications. However, a significant challenge remains in the fabrication of silsesquioxane-coated fabrics with efficient oil/water separation and enhanced antifouling performance. This study investigates fluorine-methoxylated-functionalized double-decker silsesquioxane (F-DDSQ) using a photoinitiated thiol-ene reaction and prepares a superhydrophobic coating of F-DDSQ on cotton fabric using the sol–gel method. The structure and properties of the modified fabrics were analyzed using Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurement. The F-DDSQ-fabric exhibited superhydrophobic property, with a WCA of up to 157°. Additionally, the modified fabric with excellent mechanical, physical, and chemical stability can resist a variety of external forces while keeping the coating undamaged. The coated filter fabric effectively separated different kinds of immiscible oil/water mixtures with separation efficiencies exceeding 99%. Even after 60 cycles of separating a typical dichloromethane/water mixture, the filter fabric demonstrated its durability by maintaining a high separation efficiency. Moreover, its antifouling property against contaminants such as methylene blue, soft drink, muddy solutions, and coffee powder were also examinined. This work serves as a guide for the construction of superhydrophobic coated fabric, which is intended for use in the treatment of oil-contaminated wastewater and for antifouling purposes.</p>