A multi-channel semiconductor-on-insulator (SOI) transistor includes a substrate having an electrically insulating layer thereon and a semiconductor active layer on the electrically insulating layer. A vertical stack of spaced-apart insulated gate electrodes, which are buried within the semiconductor active layer, is also provided. This vertical stack includes a first insulated gate electrode extending adjacent the electrically insulating layer and an (N−1)th insulated gate electrode that is spaced from a surface of the semiconductor active layer, where N is a positive integer greater than two. An Nth insulated gate electrode is provided on the surface of the semiconductor active layer. A pair of source/drain regions are provided within the semiconductor active layer. These source/drain regions extend adjacent opposing sides of the vertical stack of spaced-apart insulated gate electrodes. In some of these aspects, the semiconductor active layer extends between the pair of source/drain regions and the electrically insulating layer, whereas the first insulated gate electrode contacts the electrically insulating layer.