Chelsea have completed the club-record signing of Alvaro Morata from Real Madrid on a five-year contract.
The Spain striker flew into London on Thursday to have a medical and complete the formalities of a deal which could eventually cost Chelsea £70m.
The Premier League champions announced his arrival on Friday evening, and Morata will now fly out to join his new team-mates on their pre-season tour of Asia.
He told the club website: "I am so happy to be here. It's an incredible emotion to be part of this big club.
"I am looking to work hard, score as many goals as I can and to win as many trophies as possible."
Technical director Michael Emenalo said: "We are delighted to complete Alvaro's signing and welcome him to the club. We believe he can make a great impact for Chelsea and look forward to seeing him in action.
"Alvaro has proven class at the highest level and his quality will be a huge asset to Antonio and the squad."
Morata was a target for Manchester United earlier in the transfer window before Jose Mourinho moved for Everton's Romelu Lukaku.
But the 24-year-old told Sky Sports News on Thursday he is joining "the best club" in Chelsea, where he will replace Diego Costa as first-choice striker.
Morata scored three goals at last summer's European Championships and had the best goals-per-minute record of any Real Madrid player in La Liga last season after winning two Italian titles in two years on loan at Juventus.
And Sky Sports' Spanish football expert Terry Gibson believes Real will regret selling.
He said: "I think this may prove to be a mistake on Madrid's part. Morata is a dynamic striker that works the channels, he's got a great first touch.
"He'll control the ball where it is knocked up to him and he's good at attacking crosses - those attributes lend to doing well in the Premier League."