After signing for Blues, Morata said: “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 added: “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.”
Alvaro Morata hugs Real Madrid teammates farewell before leaving for Chelsea
The deal smashes the £50m Blues paid to sign Fernando Torres in 2011 – with Morata admitting he has asked the Atletico hitman for tips on succeeding at Stamford Bridge.
And it comes as a second boost of the week for Blues fans, after Antonio Conte signed a fresh two-year deal on improved terms.