Chelsea have signed centre-back Tosin Adarabioyo from fellow west London club Fulham on a free transfer, the Premier League side announced on Friday.
The 26-year-old, who arrives at Stamford Bridge on a four-year contract beginning on July 1, has made one appearance for England under-19s and has played 78 times in the Premier League.
He is the first player to join Chelsea since they announced the arrival of new head coach Enzo Maresca earlier this week, and will bolster their options at centre-back following the departure of veteran Thiago Silva.
"We are delighted to bring Tosin to Chelsea," Chelsea co-sporting directors Laurence Stewart and Paul Winstanley said in a statement.
"Throughout his career, he has showcased his maturity and defensive qualities and has gained a wealth of experience in the Premier League in recent seasons.
"He is ready to make the step up to Chelsea and work alongside the talented players in our squad. We look forward to Tosin joining up with us for pre-season."
Chelsea are looking to revive their fortunes under Maresca after finishing sixth in the table last season.
"I'm looking forward to starting work with Enzo and I'm sure the boys are too," Adarabioyo said.
"It's going to be exciting. We're going to play good football and win a lot of games. There are top players in this squad and I'm eager to play with them all."