The article presents a novel class of graphene-based in-plane micro-supercapacitors with high power and energy densities. These micro-supercapacitors, fabricated on both rigid and flexible substrates, demonstrate an area capacitance of 80.7 μF cm⁻² and a stack capacitance of 17.9 F cm⁻³. They exhibit a power density of 495 W cm⁻³, higher than that of electrolytic capacitors, and an energy density of 2.5 mWh cm⁻³, comparable to lithium thin-film batteries. The devices show superior cycling stability, retaining 98.3% of their capacitance after 100,000 cycles. They can operate at ultrahigh scan rates up to 1,000 V s⁻¹, three orders of magnitude higher than conventional supercapacitors. The in-plane geometry and high electrical conductivity of the graphene films are key factors contributing to their exceptional performance. The micro-supercapacitors are promising for miniaturized and flexible electronic applications, offering a significant advancement in on-chip micro-power sources.The article presents a novel class of graphene-based in-plane micro-supercapacitors with high power and energy densities. These micro-supercapacitors, fabricated on both rigid and flexible substrates, demonstrate an area capacitance of 80.7 μF cm⁻² and a stack capacitance of 17.9 F cm⁻³. They exhibit a power density of 495 W cm⁻³, higher than that of electrolytic capacitors, and an energy density of 2.5 mWh cm⁻³, comparable to lithium thin-film batteries. The devices show superior cycling stability, retaining 98.3% of their capacitance after 100,000 cycles. They can operate at ultrahigh scan rates up to 1,000 V s⁻¹, three orders of magnitude higher than conventional supercapacitors. The in-plane geometry and high electrical conductivity of the graphene films are key factors contributing to their exceptional performance. The micro-supercapacitors are promising for miniaturized and flexible electronic applications, offering a significant advancement in on-chip micro-power sources.