But less than six years after his departure, the Special One is back at Stamford Bridge to the delight of Blues fans — and he said it took him only a few minutes to agree to a new union.
"I had to prepare myself not to be too emotional on my arrival at the club, but obviously I am very happy," Mourinho told Chelsea TV. "It was an easy decision. I met the boss, I met the owner, and in five minutes after a couple of very short but pragmatic questions, we decided straight away. I asked the boss: 'Do you want me back?' And the boss asked me: 'Do you want to come back?' And in a couple of minutes, the decision was made."
Chelsea confirmed on Monday that the 50-year-old Portuguese coach, who on his first day at Chelsea in 2004 declared himself a "Special One," was hired on a four-year contract after completing a three-season stint at Real Madrid in which his final campaign ended without a trophy.
Mourinho's relationship with Abramovich has improved over the years, and the unpredictable manager said their divorce back in 2007 benefited both him and the club.
"It was a difficult moment because I love it here and have a big connection with the club. Also for the club, my departure it was not easy," Mourinho said. "But if you analyze it in a cool way and you leave emotions a bit apart, I think it was fantastic. Because after that I had in my career what I was aiming for, and Chelsea as a football club got important trophies after that, with important moments in the history of the club. Now we are back together and it is a great moment for both, so I think we are ready to marry again and to be happy and successful again."
Madrid released the charismatic and fiery coach from his contract, so Abramovich will not have to pay compensation to be re-united with the manager he fell out with in 2007.
"I never hide that in my career in football I had two great passions, Inter and Chelsea, and Chelsea is more than important for me," Mourinho said. "It was very hard to play against Chelsea. I did it twice, which was not so bad. Now I promise exactly the same things I promised in 2004, but with the difference we have (now), which is I am one of you."
There have been seven managers at Chelsea in the six years since Mourinho left, having won every major domestic honour at Stamford Bridge but repeatedly falling short of giving Abramovich a Champions League trophy.
"I am delighted to welcome Jose back to Chelsea. His continued success, drive and ambition made him the outstanding candidate," Chelsea chief executive Ron Gourlay said. "It is our aim to keep the club moving forward to achieve greater success in the future and Jose is our No. 1 choice as we believe he is the right manager to do just that."
Mourinho's return to Chelsea had been widely expected for weeks, after he hinted at it repeatedly during the final stretch of the season. Before flying to London, he told a Spanish TV program that he was expecting to be hired as Chelsea coach by the end of the week. And on Sunday, the Premier League's official website mistakenly published a story with the headline "Jose Mourinho makes Chelsea return," saying a deal had been completed.
Mourinho won two Premier League titles, an FA Cup and two League Cups between 2004 and 2007 with Chelsea, and his departure caused a storm of fan protests against Abramovich.
"He was and remains a hugely popular figure at the club and everyone here looks forward to working with him again," Gourlay added.
After leaving Chelsea, Mourinho went on to coach Inter, winning two Serie A titles, the Italian Cup and the Champions League. With Madrid, he won one Copa del Rey and one Spanish league title.
Chelsea said Mourinho is bringing with him three members of his coaching staff — Rui Faria, Silvino Louro and Jose Morais — who will work alongside the current team staff. He will be officially presented next Monday during a news conference at Stamford Bridge. Financial terms of the deal were not disclosed.
Abramovich will be looking to Mourinho to restore unity after the divisiveness caused by the appointment of Rafa Benitez as interim manager, who was regularly jeered by fans.
Yet, Benitez's reign ended last month with the Europa League trophy, and — more significantly — a Champions League spot secured for next season.
Europe's top prize was the only major trophy that eluded Mourinho at Chelsea between 2004 and '07. He delivered the Premier League trophy in his first season, ending the club's 50-year wait for a league title.
Although Mourinho retained the title the following year, he failed to repeat the Champions League success he'd orchestrated at his previous club, Porto, despite fielding a more expensive and star-studded squad.
Mourinho left in September 2007 following a power struggle with Abramovich.
But, while employed by Inter and Madrid, Mourinho appeared to forget his clashes with the English media and Abramovich as he started openly flirting with Chelsea.
Little was done to disguise his desire to return to west London as tensions in Madrid became increasingly fraught during the most recent season. Mourinho angered the Madrid fans and some players as well, notably goalkeeper Iker Casillas, in a stark contrast to the mutual respect and admiration he shared with his former Chelsea players.
More often this season, he's been engaged in disputes internally, creating enemies and weakening his position. The decision that most enraged fans was dropping Casillas, the captain of Madrid and Spain's world and two-time European championship-winning national team.
Real president Florentino Perez indicated that Mourinho couldn't cope with the pressure at the Santiago Bernabeu.
Mourinho was an unsuccessful player whose big break in coaching came when he was hired as an interpreter for English coach Bobby Robson at Sporting Lisbon in Portugal.
Robson took Mourinho with him to Porto and his influence increased as he took on coaching responsibilities. The duo moved to Barcelona for the 1996-97 season, and Mourinho remained at the club under Louis van Gaal following the Englishman's departure.
Mourinho returned to Portugal but failed to win any titles during stints as a senior coach at Uniao Leiria and Benfica. That changed in his first full season at Benfica's rival Porto, winning the league, Portuguese Cup and UEFA Cup in 2003.
It was the Champions League win in 2004 that convinced Chelsea to hire him.
He became the third coach to win the European Cup with two teams, with success in the 2010 final with Inter Milan where he won the Serie A title in 2009 and 2010 before being enticed to Madrid.