In this article, wafer-scale gallium nitride (GaN)-Si(100) monolithic integration material was achieved by transfer printing and self-aligned etching technology. A monolithic heterogeneous integration inverter consists of a normally-OFF Si PMOSFET and a normally-OFF GaN nMOS-HEMT was fabricated on the 2-in wafer-scale GaN-Si(100) integration platform, which overcomes the immaturity of GaN PMOSFETs. The GaN-Si(100) monolithic heterogeneous integration inverter exhibits an excellent low-level noise margin (NM $_{\text{L}}\text{)}$ of 1.69 V and a high-level noise margin (NM $_{\text{H}}\text{)}$ of 0.95 V at a supply voltage ( $\textit{V}_{\text{DD}}\text{)}$ of 3 V. The output voltage swing $\textit{V}_{\text{SW}}$ in the percentage of $\textit{V}_{\text{DD}}$ is 100%. The rise and fall times of the fabricated inverter are less than 0.1 $\mu $ s. The excellent results demonstrate the promising potential of the GaN-Si(100) monolithic heterogeneous integration devices for high-frequency drive and logic integrated circuits applications.