The Portuguese coach travelled to London to complete the formalities of a second stint in charge of the west London club after his exit from Real Madrid was confirmed, penning a four-year deal.
Mourinho was headhunted by the Blues after guiding Porto to Champions League glory in 2004, and would lead Chelsea to successive Premier League titles in 2005 and 2006, before then leaving after his relationship with owner Abramovich broke down and they parted company, officially by mutual consent at the time.
Since winning the European Cup again with Inter Milan and the Spanish title in his second season in Madrid, the 50-year-old has never made any secret of a love affair with the Chelsea faithful.
Mourinho's relationship with Abramovich has long since warmed and the Portuguese maintains it was an "easy decision" to make.
"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 chief executive Ron Gourlay insists moving to bring back the self-proclaimed 'Special One' was the only option as Chelsea looked to take the club on following the reign of interim manager Rafael Benitez, who had replaced Champions League-winning coach Roberto Di Matteo in November 2012, and after some initial difficulties guided the Blues to a third-place finish as well as winning the Europa League.
Mourinho feels with hindsight the parting of the ways back in September 2007, when he was replaced by Avram Grant, was perhaps what both needed at the time, as Chelsea have since also gone on to win the European Cup last season.
"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," he said.
"But if you analyse 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."
Mourinho feels he is coming back to Stamford Bridge as much a fan as he is the club's eighth manager since he left.
"It is exactly the same message, but now I can say I am one of you and that makes a little bit of a difference," he said.
"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.
"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."
Mourinho will be officially unveiled at a press conference at Stamford Bridge on June 10, and is set to bring assistant coaches Rui Faria, Silvino Louro and Jose Morais to Stamford Bridge where they will work alongside current first-team staff Steve Holland, Christophe Lollichon and Chris Jones.
The new manager is expected to bring in some reinforcements ahead of the new season, with £15million-rated Roma midfielder Daniele De Rossi a reported target.
One player who is certain to be an integral part of the Blues side again next season is Frank Lampard.
The 34-year-old England midfielder broke the club's long-standing goal scoring record this season and agreed a 12-month contract extension.
Lampard told BBC Sport: "He's taken that (a winning mentality) everywhere he's gone with him. He creates a spirit in his squads that you can see from the outside is very, very strong. He's a top-class manager, we all know that."
Mourinho's previous spell of just over three years at Stamford Bridge was his longest at any club in a nomadic career to date.
But he said: "I am much more ready to establish myself in the club for a long time.
"When you look at the profile of the Chelsea squad, I think it's what they need at this time.
"From my time I have four or five boys, the older ones obviously, and they are very important for the club and the balance of the squad.
"But there is a young squad with a lot of talent and they need stability to reach a higher point of their evolution. I hope I can give them that."
Among the latter group is David Luiz, who has been the subject of speculation suggesting he could leave the club if Mourinho was appointed.
But the 26-year-old Brazil international was included on Mourinho's list today of those he is looking forward to working with.
Mourinho said: "I have a four-year contract so if I read the situation with the age of (Juan) Mata, (Eden) Hazard, Oscar, Luiz, it will be good for me to work with them and improve the team that we have.
"I like very much that kind of profile, younger players with long-term space for improvement and development."