Single layers of graphene obtained by mechanical exfoliation of highly oriented pyrolytic graphite and deposited on a SiO2/n+‐Si substrate were irradiated with high‐energy (500 keV) C ions. Controlled amounts of defects were introduced in graphene by a precise control of the ion fluence, ranging from 1× 1013 to 1× 1014 cm− 2. Scanning capacitance spectroscopy (SCS) was used as non‐destructive characterization technique to probe the effect of irradiation defects on the electrical properties of graphene. A wider variation between the capacitance curves measured at different positions on irradiated graphene is found in comparison with the pristine graphene. The quantum capacitance per unit area C'_\rmq was extracted from raw data. In particular, an increase of C'_\rmq is associated to the damaged regions.