GaN power electronic devices, such as the lateral AlGaN/GaN Schottky barrier diode (SBD), have received significant attention in recent years. Many studies have focused on optimizing the breakdown voltage (BV) of the device, with a particular emphasis on achieving ultra-high-voltage (UHV, > 10 kV) applications. However, another important question arises: can the device maintain a BV of 10 kV while having a low turn-on voltage (V_on)? In this study, the fabrication of UHV AlGaN/GaN SBDs was demonstrated on sapphire with a BV exceeding 10 kV. Moreover, by utilizing a double-barrier anode (DBA) structure consisting of platinum (Pt) and tantalum (Ta), a remarkably low V_on of 0.36 V was achieved. This achievement highlights the great potential of these devices for UHV applications.