Morata, 25, moved to Juve during the summer of 2014 after being restricted to a secondary role by Carlo Ancelotti during the 2013-2014 campaign.
The Spain international won the Serie A title twice with Juventus and reached the Champions League final in 2015 after scoring two goals against Real in the semi-final.
In the summer of 2016 Los Blancos decided to activate a buy-back clause included in his sale to the Italian giants.
Upon his return, Morata scored 15 goals under Zidane's leadership to help Real to win both the Champions League and La Liga title last season.
However, it had previously emerged that the Spaniard wanted to leave Real again after having grown frustrated with Zidane due to his continued faith in Karim Benzema.
"[I returned to Real Madrid] because there were contractual agreements to respect. The disappointment was enormous. I found myself right back where I had started. They treated me like the kid that I was before my two years in Italy," the current Chelsea star admitted during an interview with La Gazzetta Dello Sport.
"My two years at Juve were great. I was just a kid when I arrived and I was a real footballer when I left. For a Spaniard, Italy is the best place to live. You've got all the beauty, history, art, good food and fashion. I would never have left Italy and Juve."
Antonio Conte took advantage of Morata's frustration to bring him to Stamford Bridge in the summer, with the Chelsea boss having already lured him to Juventus in 2014 only days before resigning from his post at La Vecchia Signora.
"I came here [to Chelsea] because of Conte. We started talking about my eventual transfer last spring and now I am finally here in London," Morata admitted. "He is demanding but he gets the best out of his players. You can tell that he knows what it is like to be at a big club, first as a player, then as a coach."
"There have been a number of favourable situations [to ease my adaptation to London], starting with the manager. I knew Conte and I had no problems fitting into his ideas of football. The second is the environment as I have been very well welcomed by my teammates. The presence of the Spaniards, with [Cesar] Azplicueta, [Marcos] Alonso, [Cesc] Fabregas and Pedro have made the things easier. The third is my wife Alice Campello: he has come with me to London."