Ordered mesostructured tungsten carbide and graphitic carbon composites (WC/C) with nanocrystalline walls are fabricated for the first time by a temperature-programmed carburization approach with phosphotungstic acid (PTA) as a precursor and mesoporous silica materials as hard templates. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling the silica template (SBA-15 or KIT-6), carburizing temperature (700–1000 °C), the PTA-loading amount, and the carburizing atmosphere (CH4 or a CH4/H2 mixture). A high level of deposited carbon is favorable for connecting and stabilizing the WC nanocrystallites to achieve high mesostructural regularity, as well as promoting the carburization reaction. Meanwhile, large pore sizes and high mesoporosity of the silica templates can promote WC-phase formation. These novel, ordered, mesoporous WC/C nanocomposites with high surface areas (74–169 m2 g−1), large pore volumes (0.14–0.17 cm3 g−1), narrow pore-size distributions (centered at about 3 nm), and very good oxidation resistance (up to 750°C) have potential applications in fuel-cell catalysts and nanodevices.