Enhanced performance in AlGaN/GaN Schottky barrier diodes (SBDs) is investigated using a nanowire hybrid tri-anode structure that integrates 3-D Schottky junctions with tri-gate transistors. The fabricated SBDs presented an increased output current density with an improved linearity, above 1 A/mm at 5 V when normalized by an effective anode width, over three orders of magnitude lower reverse leakage current and superior heat dissipation. The sidewall Schottky contacts reduced the turn-on voltage and eliminated the nonideality caused by the AlGaN barrier. The large surface area of the tri-gate architecture greatly enhanced heat dissipation and largely reduced the average temperature as well as thermal resistance of the integrated tri-gate transistors. The trench conduction near SiO2/GaN interface, formed under forward bias at both sidewalls and bottom of nanowire trenches, compensated part of the self-heating degradation and improved the output linearity of the device. Optimal design for the tri-anode structure, based on a model of critical filling factor, was proposed to surmount the issue of partial removal of 2-D electron gas (2DEG), unveiling the potential of nanostructured GaN devices to achieve comparable or even larger output current than counterpart planar devices.