This work presents a GaN lateral bidirectional electrostatic discharge (ESD) clamp (B-ESD-C1), featuring a floating-gate monolithic bidirectional switch (MBS) and a regulating capacitor ( ${C}_{\text {GG}}$ ) in parallel connection between two floating gates. In different directional ESD events, B-ESD-C1 with ${C}_{\text {GG}}$ of 10 pF is provided with a low triggering voltage ( ${V}_{\text {trig}}$ ) of about 10 V and a second breakdown current ( ${I}_{\text {s}}$ ) of 5 A. Although the presented B-ESD-C1 exhibits similar ESD robustness with the clamp based on two p-GaN HEMTs and two regulating capacitors, the presented clamp possesses a smaller chip area and shows an improved consistency in its forward and reverse ESD robustness. It is also proven that the regulating capacitor of the presented B-ESD-C1 pays an important role on its ${V}_{\text {trig}}$ and ${I}_{\text {s}}$ . Through changing the regulating capacitor, an expected ${V}_{\text {trig}}$ can be acquired. Furthermore, the possible fabrication process of the presented B-ESD-C1 can be same as that of p-GaN high-electron mobility transistor (HEMT), making the ESD design more convenient.