Barkley was not given a squad number for the new season, having made just six Premier League appearances last season.
The midfielder was signed from Everton in January 2018 but never managed to solidify his place as a regular starter under Antonio Conte, Maurizio Sarri, Frank Lampard or Thomas Tuchel.
He spent the 2020-2021 season on loan at Aston Villa, where he appeared to be striking up a promising partnership with Jack Grealish, but his form tailed off and his move was not made permanent.
Three days before the close of the transfer window, Chelsea confirmed it has agreed to cut ties with the 28 year-old, whose deal was to expire at the end of the season.
Barkley has been linked with a move back to Everton and could be the first of several exits from Stamford Bridge this week, with Billy Gilmour, Conor Gallagher, Armando Broja and Trevoh Chalobah all drawing interest, according to reports. Callum Hudson-Odoi, meanwhile, is set to join Bayer Leverkusen on loan.