AbstractChemical oxidation is used to cut and unzip multi‐walled carbon nanotubes in the transverse direction and the axial direction to form graphene oxide nanoribbon (GONR). Ruthenium oxide/reduced graphene oxide nanoribbon composite (RuO2/rGONR) with a 72.5 wt% RuO2 loading is synthesized through an aqueous‐phase reaction, in which GONR is served as starting material, followed by mild thermal treatment in ambient air. The resulting RuO2/rGONR composite achieves specific capacitance up to 677 F·g−1 at the current density of 1 A·g−1 in three‐electrode system using 1 mol·L−1 H2SO4 as electrolyte. The resultant electrode exhibits an excellent rate capability (91.8% retention rate at 20 A·g−1). Especially, the symmetric supercapacitor assembled on the basis of RuO2/rGONR electrode delivers high energy density (16.2 Wh·kg−1) even at the power density of 9885 W·kg−1, which is very essential for supercapacitors.