Three-dimensional germanium-based semiconductor devices formed on globally or locally isolated substrates are described. For example, a semiconductor device includes a semiconductor substrate. An insulating structure is disposed above the semiconductor substrate. A three-dimensional germanium-containing body is disposed on a semiconductor release layer disposed on the insulating structure. The three-dimensional germanium-containing body includes a channel region and source/drain regions on either side of the channel region. The semiconductor release layer is under the source/drain regions but not under the channel region. The semiconductor release layer is composed of a semiconductor material different from the three-dimensional germanium-containing body. A gate electrode stack surrounds the channel region with a portion disposed on the insulating structure and laterally adjacent to the semiconductor release layer.