The Spain international, who will wear the number 21 shirt he also sported during his time at Real Madrid, arrives at Butarque with the aim of reviving his career and helping the club return to the top flight two years after relegation. Thousands of supporters turned out to welcome him on Friday, hours after the loan, which includes a purchase option, was made official.
"I want to thank Leganés for all their affection. I'm a very sentimental guy, and even though there are a lot of jokes about my career, I always try to go where I feel most valued and most loved," Morata said at his presentation.
"In life, not everything is about winning trophies and playing the Champions League. I've had some difficult years. I've had to fight against myself many times, against a lot of opinions. I feel like it's my first day, like a young lad signing for his first club.
"It's lovely to be in Madrid, at home. I could have gone somewhere with less footballing demands - the Segunda División is often harder than the Primera. I'm here to help meet the club's goals."
Asked how the move came together, Morata explained the conversation began with his coach and friend, Cesc Fàbregas.
"He told me I wasn't going to be important for the project. I spoke with my agent, Juanma. We started looking at options - plenty of offers from Spain, others from European clubs playing in the Champions League. I needed to find myself again as a player. I have a lot of labels attached to me over my career, but the chance Leganés is giving me to be happy on a football pitch again is fantastic."
Morata, who has scored 37 goals in almost 90 caps for Spain, admitted he could feature against Eldense on Saturday, though the decision is not his to make. He recalled attending a Leganés-Atlético match at Butarque as a boy, working as a ball boy: "I'd never thought about playing here, but it's a lovely story to remember," he said, visibly moved.
On the responsibility that comes with being the marquee signing of the summer in the second tier, he added: "Leganés has to be among the candidates to go up to the Primera División. I've had pressure since I was young, and it often helps. Every point in the Segunda makes a real difference."
Asked what he dreams of achieving, Morata said simply: "We dream of being in the Primera División next year, and that the club can carry on with the project it has. If we're in the top flight, a big objective will have been met."