A FinFET including a substrate, a plurality of isolation structures, a plurality of blocking layers, and a gate stack is provided. The substrate has a plurality of semiconductor fins. The isolation structures are located on the substrate to isolate the semiconductor fins. In addition, the semiconductor fins protrude from the isolation structures. The blocking layers are located between the isolation structures and the semiconductor fins. The material of the blocking layers is different from the material of the isolation structures. The gate stack is disposed across portions of the semiconductor fins, portions of the blocking layers and portions of the isolation structures. In addition, a method for fabricating the FinFET is also provided.