Published Monday, 18 April 2011
Her character will remain on screen until early 2012 and will depart in an "explosive" storyline to begin next month.
"Viewers will see Becky go into meltdown when social services start investigating her 'purchase' of her sister's son Max," a statement from the channel said.
"Believing Tracy Barlow has reported her to the authorities, Becky goes on the rampage - putting Tracy's life in jeopardy and risking the future of her marriage to Steve McDonald."
Katherine, who joined the show in February 2006, said: "It's been one of the hardest decisions of my life. I love Coronation Street and everyone here. I have had the most blissful five years, I wouldn't change one moment of it - but it feels like the time is right to say goodbye to Becky."
The character of Becky McDonald was a former drug addict and jailbird, who turned her life around with the help of Roy and Hayley Cropper.
She was briefly engaged to Jason Grimshaw before getting together with Steve McDonald when he provided her with an alibi after she was arrested for going on a drunken rampage.
Steve and Becky had two weddings, after she turned up so drunk at the first one the registrar refused to marry them.
Recently the character, desperate for a child of her own, was seen "buying" her nephew Max from her sister Kylie, and looting the corner shop as Sunita lay injured following the tram crash.