We report a new and general strategy for efficient injection of carriers in active nanophotonic devices involving the synthesis of well-defined doped core/shell/shell (CSS) nanowire heterostructures. n-GaN/InGaN/p-GaN CSS nanowire structures were grown by metal-organic chemical vapor deposition. Electron microscopy images reveal that the CSS nanowires are defect-free single crystalline structures, while energy-dispersive X-ray linescan profile studies confirm that shell thickness and composition can be well controlled during synthesis. Photoluminescence data further show that the optical properties are controlled by the CSS structure with strong emission from the InGaN shell centered at 448 nm. Importantly, electrical devices made by simultaneously contacting the n-type core and outer p-type shell of the CSS nanowires demonstrate that in forward bias these individual nanowires behave as light-emitting diodes (LEDs) with bright blue emission from the InGaN shell. The ability to rationally synthesize gallium nitride-based radial heterostructures should open up new opportunities for nanophotonics, including multicolor LEDs and lasers.