The Spain international arrives for a reported $A115 million after the Stamford Bridge club missed out on re-signing Romelu Lukaku, who joined Manchester United from Everton for $A123 million.

Torino forward Andrea Belotti, Borussia Dortmund striker Pierre-Emerick Aubameyang and Manchester City's Sergio Aguero were all purported targets for the Premier League champion after boss Antonio Conte told Diego Costa he was not part of his future plans.

Conte and Morata missed out on working with each other at Juventus when the former took on the Italy job in July 2014, but the 24-year-old striker is now set to spearhead his title defence.

"I am so happy to be here," said Morata. 

"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."

Although he insists it was his decision to leave for Stamford Bridge, the 24-year-old concedes that it is difficult to be moving on after just one more year in Spain.

"Today is a special day, different…" Morata wrote on Twitter. "There are many things I would like to say now, there are many feelings, many memories that now gather in my head.

"Today my second spell at Real Madrid finishes, today a new phase of my career begins. I'm sure that some will not understand my decision, others will certainly not support it... but in the end that's what it is, my decision. A decision well thought through and considered.

"I'm leaving home, because that's how I feel at Real Madrid. I'm going with the clear conscience of someone who gave everything in every training session, in every minute in which I was lucky enough to wear the shirt, with the calm of having been important in an amazing year in which we lifted four trophies, a year that I'm sure neither you nor I will ever forget..."