A gate cut isolation including an air gap and an IC including the same are disclosed. A method of forming the gate cut isolation may include forming an opening in a dummy gate that extends over a plurality of spaced active regions, the opening positioned between and spaced from a pair of active regions. The opening is filled with a fill material, and the dummy gate is removed. A metal gate is formed in a space vacated by the dummy gate on each side of the fill material, and the fill material is removed to form a preliminary gate cut opening. A liner is deposited in the preliminary gate cut opening, creating a gate cut isolation opening, which is then sealed by depositing a sealing layer. The sealing layer closes an upper end of the gate cut isolation opening and forms the gate cut isolation including an air gap.