Gate-all-around integrated circuit structures having depopulated channel structures, and methods of fabricating gate-all-around integrated circuit structures having depopulated channel structures using multiple bottom-up oxidation approaches, are described. For example, an integrated circuit structure includes a vertical arrangement of nanowires. All nanowires of the vertical arrangement of nanowires are oxide nanowires. A gate stack is over the vertical arrangement of nanowires, around each of the oxide nanowires. The gate stack includes a conductive gate electrode.