The Portuguese coach, 50, travelled to London on Monday to complete the formalities of a second stint in charge at Stamford Bridge 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 leaving after his relationship with owner Roman Abramovich broke down.
Success has followed elsewhere - a treble with Inter Milan and the Spanish title in his second season at Madrid - but Mourinho has never attempted to play down his love affair with the Chelsea faithful.
"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 on Chelsea TV.
"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."