Carbon ions are used to heat the precompressed deuterium–tritium (DT) fuel in a cone-guided fast ignitor scheme with an areal mass density of about 2.6 g cm−2. An ultra-intense laser pulse with a focal intensity of 1.45 × 1022 W cm−2 accelerates the carbon ions to an energy of 450 MeV from a homogeneous layer of 0.2 g/cm3 density, which fills the head of the gold cone. Pellet ignition was observed in hybrid numerical simulations for a laser energy of about 65 kJ in a rectangular pulse of 4 ps duration. This corresponds to estimated overall efficiencies of more than 24% for ion acceleration and 17% for core heating. Reducing the laser intensity to the value 5 × 1021 W cm−2, carbon ions with the energy of 175 MeV will be accelerated, and ignition occurred in hydrodynamic simulations for a laser energy of 115 kJ at a reduced heating efficiency of 6%. The comparison with ignition of a large-scale DT pellet, showing similar hydrodynamic characteristics and heated by in situ accelerated DT ions with 10 MeV mean energy, demonstrates the advantage of the carbon ion ignitor beam due to the more effective acceleration and expected higher directionality.