The actress, who plays former Rovers landlady Michelle Connor, wants to try something new.
Kym, 42, told The Sun: “It’s been an incredibly difficult decision but it feels like the right time.”
Bosses were desperate for her to stay on as Michelle Connor. Executive producer John Whiston said: “We’ll be really sad to lose her.”
Yesterday she told The Sun: “When I was lucky enough to be offered four episodes I could never in my wildest dreams have thought I’d be here 13 years later.
“It’s been an incredibly difficult decision but it feels like the right time for me to explore some other roles.”
Kym, 42, first found fame on talent show Popstars which saw her land a place in group Hear’Say.
She had West End roles before her chance on Corrie. She proved so popular her role was made permanent.
Last night Coronation Street executive producer John Whiston confirmed her departure and said: “Kym has done a fantastic job.
“She has brought incredible heart and humanity to some hugely important stories. We will be really sad to lose her when she goes but totally understand that, after dedicating herself to the show for so long she now fancies trying something else.”
She will leave later this year. Show bosses have decided not to kill off her character and hope that Kym will return in the future.
A TV insider explained: “Kym has loved her time on Corrie and has lifelong friends on set, but she is ready for a new challenge.
“She loves the role of Michelle and she told bosses she hoped they would agree to keep the door open in the future. They have done — so everyone is leaving on great terms.
“The writers will want the character to go out with a bang.”
And Kym added: “This isn’t the last you’ve heard of Michelle Connor, she’ll be back! I can’t wait to see what the writers have in store for the future.”