Tomas Kalas will spend a second season loan at Fulham after signing a new four-year contract with Chelsea.
The 24-year-old Czech international centre back was a key part of the Fulham side which finished sixth in the Championship last season only to be beaten in the play-off semi-finals by Reading.
Kalas is the 19th player to be loaned out by Chelsea already this summer, with many more expected to be sent out on short-term deals before the transfer window closes.
Kalas' Chelsea team-mate Lucas Piazon also signed up to a second season-long loan with Fulham earlier this month as they look to go one better and earn promotion back to the Premier League.