Chelsea announced on their official website that 20-year-old midfielder Leo Castledine has joined Championship side Middlesbrough.
"We thank Leo for his contribution to Chelsea and wish him well in the next chapter of his career at Middlesbrough," the London club said in a statement.
Castledine joined Chelsea's academy in March 2020. He made his senior debut in the second leg of the League Cup semi-final against Middlesbrough, coming on as a late substitute in the London club's 6–1 victory.
According to information provided by Transfermarkt.com, the player's transfer value is 1.1 million euros.