Abstract In this work, a SiC split-gate MOSFET integrating a superjunction (SJ) structure and a P-type shielding layer (SGSJCIMOSFET) is proposed and systematically investigated using TCAD simulations. The proposed device simultaneously improves the trade-off among breakdown voltage (BV), specific on-resistance (RON,sp), and switching performance. Compared with conventional VDMOSFET and split-gate MOSFET, the SGSJCIMOSFET achieves an enhanced BV of 3718 V and a reduced RON,sp of 1.16 mΩ·cm², resulting in an approximately 4.6× improvement in Baliga’s figure of merit. In addition, the combined effects of the split-gate and SJ structures significantly suppress the gate-to-drain capacitance to 15.2 pF/cm², leading to improved high-frequency performance. The incorporation of the P-type shielding layer effectively redistributes the electric field and reduces the peak oxide electric field from 4.15 MV/cm to 2.06 MV/cm. These results demonstrate that the proposed SGSJCIMOSFET is a promising candidate for next-generation high-voltage and high-frequency power applications.