Thin film core-shell fin and nanowire transistors are described. In an example, an integrated circuit structure includes a fin on an insulator layer above a substrate. The fin has a top and sidewalls. The fin is composed of a first semiconducting oxide material. A second semiconducting oxide material is on the top and sidewalls of the fin. A gate electrode is over a first portion of the second semiconducting oxide material on the top and sidewalls of the fin. A first conductive contact is adjacent the first side of the gate electrode, the first conductive contact over a second portion of the second semiconducting oxide material on the top and sidewalls of the fin. A second conductive contact is adjacent the second side of the gate electrode, the second conductive contact over a third portion of the second semiconducting oxide material on the top and sidewalls of the fin.