The actor - who plays Kevin Webster in the ITV soap - has been following a strict diet and lifestyle regime at the £350-a-week clinic and should be home in 'days'.
A friend of the star told The Sun: “He now feels better than he has done in years. He really believes he’s turned the corner this time.
"Michael has found rehab a tough slog."
'Corrie' bosses are understood to have paid for the 49-year-old's treatment after he admitted to taking cocaine and drinking heavily following his trial for child sex offences last year, which he was cleared of.
“He realised it was probably his last chance with Coronation Street bosses and wanted to give it his best shot," the source continued.
“He purposely asked friends and family to stay away so he could be totally focused.
“He was determined to give it a real good go and didn’t want any kind of distraction.
“Apart from the odd phone call, he has had no contact with his family or friends.”
The actor checked into the undisclosed clinic in March after 'the toughest year of his life'.
A source told the Sunday Mirror at the time: “Michael has taken himself away from all temptation and is sorting himself out."