Nanoscale multilayer C/Cr coatings (bilayer thickness ∼2 nm) were produced by the combined steered cathodic arc/unbalanced magnetron deposition technique. The mirror-polished M2 substrates were treated by Cr+ ion etching/implantation followed by the deposition of a 0.25 μm thick CrN base layer. A 1.6 μm thick C/Cr multilayer coating was then deposited by non-reactive unbalanced magnetron sputtering while rotating the substrates in front of three graphite and one Cr targets. During the multilayer deposition, a bias potential between −65 and −95 V was applied to the substrates. The ion flux measured by a flat electrostatic probe was 1.2 mA cm−2 and the deposition rate was 0.4 μm h−1, which resulted in ion-to-neutral ratio of Ji/Jn=5.2. Cross-sectional transmission electron microscopy diffraction and Z-contrast imaging investigations revealed a novel nanostructure in which the basic nano-lamellae obtained as a result of substrate rotation in front of the C and Cr targets were modified by ion-irradiation-induced nanocolumnar structure. The intense ion-irradiation of the immiscible film components caused local enrichment of Cr and C that propagated in the growth direction resulting in Cr-rich nanocolumns separated by C-rich boundaries in an overall amorphous structure. Tribological studies of the composite C/Cr coatings were conducted using a pin-on-disk apparatus under a load of 5 N, at velocities of 0.13–0.15 m s−1 and for distances of ∼500 m in dry nitrogen (∼0% humidity) and open air (30% relative humidity). Results indicated that the C/Cr composite coatings provided friction coefficients of 0.7–0.8 in dry nitrogen, while the values were significantly lower in open air, 0.21–0.24, during sliding against both the coated and uncoated balls for coatings deposited at bias voltage of −75 V. The friction coefficient decreases to 0.16 when the bias voltage of −95 V was used.