After spending the 2021-22 campaign on loan at Norwich City, Gilmour was hoping to challenge for a first-team role under Thomas Tuchel back in West London this season.
However, the 21-year-old Scotland international is expected to leave Stamford Bridge this summer, with N'Golo Kante, Mateo Kovacic, Jorginho, Ruben Loftus-Cheek and Conor Gallagher all preferred ahead of him.