This paper presents a breakdown voltage enhancement technique for power AlGaN/GaN HEMTs by using novel Air-bridge Field Plate (AFP). The device features a metal field plate that jumps from the source over the gate region and lands between gate and drain. Simulation results show that the HEMTs with Air-bridge Field Plate can provide a new degree of freedom to modulate the device surface electric field. In a device with gate to drain distance of 6 µm, gate length of 0.8 µm, two times higher forward blocking voltage of 450 V was obtained at VGS = −5 V when compared to a device with an optimized conventional field plate device (240 V) for a given process.