The present disclosure is directed to methods for the formation of high-voltage nano-sheet transistors and low-voltage gate-all-around transistors on a common substrate. The method includes forming a fin structure with first and second nano-sheet layers on the substrate. The method also includes forming a gate structure having a first dielectric and a first gate electrode on the fin structure and removing portions of the fin structure not covered by the gate structure. The method further includes partially etching exposed surfaces of the first nano-sheet layers to form recessed portions of the first nano-sheet layers in the fin structure and forming a spacer structure on the recessed portions. In addition, the method includes replacing the first gate electrode with a second dielectric and a second gate electrode, and forming an epitaxial structure abutting the fin structure.