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 a selective bottom-up approach, are described. For example, an integrated circuit structure includes a vertical arrangement of nanowires above a substrate. The vertical arrangement of nanowires has one or more active nanowires above one or more oxide nanowires. A first gate stack is over and around the one or more active nanowires. A second gate stack is over and around the one or more oxide nanowires.