In one aspect, a method of fabricating a nanowire FET device includes the following steps. A layer of III-V semiconductor material is formed on an SOI layer of an SOI wafer. Fins are etched into the III-V material and SOI layer. One or more dummy gates are formed over a portion of the fins that serves as a channel region of the device. A gap filler material is deposited onto the wafer. The dummy gates are removed selective to the gap filler material, forming trenches in the gap filler material. The SOI layer is removed from portions of the fins within the trenches thereby forming suspended nanowire channels in the channel regions of the device. The trenches are filled with at least one gate material to form one or more replacement gates surrounding the nanowire channels in a gate-all-around configuration.