Herein, we demonstrated an “interposer”-style integration of In2O3 FET-based gate-driver circuitry wire bonded to an AlGaN/GaN high electron mobility transistor (HEMT) device grown on a GaN-on-Si substrate, and its feasibility for power electronics was discussed. The normally-on AlGaN/GaN HEMT exhibited a threshold voltage of −2.8 V, with a maximum drain current density of 265 mA/mm. The device also showed good off-state performance, such as a high ON/OFF ratio (Ion/Ioff) of ∼1010 with a breakdown voltage of ∼445 V and an off-state leakage current of ∼10−12 A. The low-temperature processed In2O3 driver circuitry exhibited a high gain of ∼64 and a maximum operating frequency of 2 kHz. The temperature-dependent study of the voltage transfer characteristics (VTC) of In2O3 driver circuitry exhibited stable operation up to 125 °C. An integrated In2O3 driver circuitry with GaN HEMT was demonstrated, marked by a 50 mA/mm drain current for circuit response of one cycle during the ON state. These results pave the way for future monolithic integration of oxide semiconductor-based gate-driver circuitry with power switches for energy-efficient integrated circuits.