England international Rose Barkley, 24, has signed a five-and-a-half-year deal with last season’s Premier League champions from Everton and will wear the No 8 shirt.
Chelsea announced the transfer on Friday, confirming the 24-year-old midfielder had completed a £15 million move to Stamford Bridge.
“I’m overwhelmed, I’m looking forward to it and I’m really excited to get started,” said Barkley.
“To be given a fresh start at a new club like Chelsea, it’s unbelievable for me. I’m looking forward to continuing where I left off at the end of last season and hoping to improve and add more goals to my game.”
The playmaker also has two goals in 22 caps for England, having represented the Three Lions at the 2014 World Cup and Euro 2016.