After a tumultuous season the 50-year-old is poised to leave Real Madrid and looks certain to rejoin the current European champion having, as several outlets revealed last week, agreed a deal that will see him return to west London after a six-year absence.
"It will increase the charm of the Premier League and Chelsea will fight for the title," Mancini told Gazetta Extra Time when asked about Mourinho's possible return to the league.
Mourinho is set to replace interim manager Rafa Benitez, whose contract expires at the end of the campaign, and Mancini feels the Spaniard has excelled at Chelsea, despite a troubled relationship with the club's supporters.
"Maybe he was weighed down by his past in Liverpool, but from the professional point of view, he has got the most out of the club," Mancini explained. "He's led Chelsea to the final of the Europa League and is third in the league."
It has been suggested that Mancini's own days at Manchester City might be numbered if he fails to beat Wigan in the FA Cup final, but the Italian believes those predicting his demise have ulterior motives.
"It is false that my future depends on Saturday's FA Cup final at Wembley," he insisted. "The truth is that I am an Italian coach and City have broken the order of English football. Now here we are and it bothers them.
"They are fictional stories in the British press. It is absolutely not true and I have never felt in danger. They criticize me for second place, but if this was a valid argument, they should fire everyone, apart from [Sir Alex] Ferguson who won the Premier League and [Michael] Laudrup who won the League Cup.
Mancini continued to suggest that the UK media doesn't enjoy seeing City contend for titles.
"Until a couple of years ago English football, with its earnings, was in the hands of Manchester United, Chelsea and Arsenal. Now here we are and it bothers them," Mancini stated. "The City from 2011 to today won three trophies and if we win the FA Cup it will become four. Not bad for a club that was dry for 35 years."