The Portuguese, who led Chelsea to back-to-back titles during his initial spell at the club between 2004 and 2007, has signed a new four-year deal to be the Blues' new manager after leaving Real Madrid in the summer.
Mourinho famously described himself as a "special one" at his first unveiling nine years ago, but he was a bit more restrained this time. Speaking to about 250 journalists at Stamford Bridge, the 50-year-old said: "I am the happy one. I am very happy."
He added: "Time flies. A lot of things happened in my professional life in the last nine years, but I have the same nature, I am the same person, I have the same heart, I have the same kind of emotions related to my passion for football and my job, but I am a different person in this moment.
"If I have to describe myself, I would describe myself as a very happy person because it's the first time I arrive in a club where I already love the club."
Mourinho left the club by mutual agreement six years ago, with many observers pointing to a perceived breakdown in his relationship with owner Roman Abramovich.
But he said: "First of all, that's not true. I read and I keep hearing that I was fired, I was sacked, we had a complete breakdown of our relationship - that was not true. Many didn't believe that but it was a mutual agreement. We thought it was best for both of us, for me and the club."
Mourinho won two Barclays Premier League titles, one FA Cup and two League Cups during his three-year spell at Stamford Bridge. The former Inter Milan boss has now set his sights on achieving even more success during his new period at the club, where he has signed a four-year contract.
"I want to believe it's possible. I always trust my work," he said. "In this case I know many of the people that belong to the club and I know the kind of mentality people have here and my career was built and based on success where I was able to reach success and to win trophies.
"I want everyone to work hard, work with quality. The club means much more compared to ourselves. We are no one without the club. If we work well success will arrive."
Source: PA
Source: PA