The daunting news for the Blues' Premier League rivals is that his ability to create a winning team appears undiminished, even if it takes more than this season to achieve it with his current group.
Almost six years after leaving Stamford Bridge in acrimonious circumstances and following a successful spell at Inter Milan and a stint which delivered success and vitriol in equal measure at Real Madrid, Mourinho returned 'home' to London and to Chelsea in June.
The 50-year-old, who announced his arrival as the Special One nine years earlier, immediately went on a charm offensive and denied he had hoped to be appointed Sir Alex Ferguson's successor at Manchester United above a reunion with Roman Abramovich.
"Maybe I am going to be the Godfather," said Mourinho, in the summer as the battle to succeed Ferguson as the Premier League's number one manager began.
Mourinho pointed out he is the only Premier League boss to have won the Champions League; something he has achieved twice while, in comparison, Arsene Wenger at Arsenal has been trophyless for eight seasons.
In his absence Abramovich's Chelsea achieved the Holy Grail, winning the European Cup in 2012 and a third title will surely be a target for Mourinho.
The Portuguese is loved in west London for delivering Chelsea's first championship in 50 years in 2005 as part of a haul which made him the club's most successful manager.
He could add to the silverware in 2014, with Chelsea well placed in the Premier League and in the Champions League knockout stages - something which eluded them as defending champions last term - as well as in contention in the cup competitions.
Mourinho has been at pains to point out that this is the most competitive Premier League in years, with Arsenal, United, Manchester City, Tottenham and Liverpool all rivalling Chelsea for the title. Winning would be a greater achievement than in his first season at Stamford Bridge.
"To win when a club is not historically a winner is a hard step," Mourinho said recently.
"But I think winning the title this season would be a bigger achievement.
"In my time it was just three teams fighting for the title. Now it's six. And the difference between the three and the rest was a big distance.
"And in this moment the distance between the six is short and the difference between the six and the next three, four is also short. Nobody knows what can happen.
"I don't remember in one of these fixtures that all of us, all the six contenders, when we win all of us at the same time.
"In Spain they are complaining the championship is not good. In Germany they are complaining the championship is not good.
"We should not complain about our Premier League. We should say it's the best championship in the world."
Chelsea have won the Premier League once since Mourinho's departure - Carlo Ancelotti's double-winning campaign in 2009-10 - but their challenge has been resurrected by the Portuguese.
After finishing 25 points off the pace in sixth place in 2011-12 and 14 adrift in third last season, he has added a steel and a guile which was missing.
He has quickly marginalised anyone who has compromised his approach.
The fact Mourinho has been able to do without the likes of World Cup winner Juan Mata and Brazil defender David Luiz at times shows the options at his disposal.
The squad is full of talent, but the balance could be questioned, particularly with six players vying for the playmaker roles behind a lone striker and a lack of cover at central defence.
Mourinho has pointed out the 'profile' of the squad is one in transition, something he must oversee.
That includes deciding on the futures of four mainstays of yesteryear.
John Terry, Ashley Cole, both 33 this month, and Frank Lampard, 36 in June, are all in the final year of their contracts.
All three could play on and have shown, to some extent, personal revivals under Mourinho, but their boss may decide the time is up.
He will also have a decision to make regarding Petr Cech - to keep the goalkeeper as his number one or to draft in Thibaut Courtois, who is a wanted man after impressing in three seasons at Atletico Madrid.
Those are subjects for another day. For now, Mourinho is focused on the present and immediate future, bidding to show his appetite for success is just the same now as it was when he first arrived at the club in 2004.