She has described her role as Stella as "a revelation", but added:
"Creatively I need to play other roles".
Producer Stuart Blackburn has wished Michelle "every happiness" and promised "the tour de force that is Stella Price will leave with a bang".
Michelle will depart the cobbles next April, with her final scenes expected to be aired in June 2014.
Stella has been at the centre of a number of high-profile storylines since her arrival in 2011, including reuniting with her estranged daughter Leanne and a turbulent relationship with gambling addict Karl.
"So much has happened to the character since we discovered she was Leanne's real Mum," said the actress.
"From catching Karl with barmaid Sunita to her near-death experience in the Rovers fire - I've loved playing Stella and will be very sorry to leave her behind.
"Creatively I need to play other roles and I've ambitions as an actress that I'd like to fulfil.
"I'm also looking forward to spending more time with my daughter Maia."
Sue Johnston, who plays Collins' on-screen mother, Gloria, is also expected to leave the soap around the same time, and John Michie - dastardly Karl - will leave screens later this year.
It feels like a bit of an exodus of late, with long-running stars William Roache and Michael Le Vell temporarily written out of the show and Chris Fountain spectacularly axed earlier this week. Let's hope producers have some exciting new characters for us!