The Taggart star leaves Corrie in September after two years playing scoundrel Karl Munro and will go straight to playing consultant neurosurgeon Guy Self in the BBC hospital drama.
John said: “It’s a complete change from scally to surgeon! I’ve never done medical drama before but I have quite a few medics in the family, so I’ve got loads of people to talk to.
“One of my good friends is John Collee, who is a doctor and a writer. He wrote Paper Mask, about a porter becoming a bogus doctor. He’s set up a load of stuff for me – his brother’s an anaesthetist and I can go in and see an operation.”
He joked: “My mum was a nurse and always wanted me to be a doctor not an actor so finally half her wish has come true!”
Oliver Kent, executive producer of Holby City, said: “We’re very excited about John joining the Holby City family. He’s a great addition to the show and viewers can look forward to seeing some explosive storylines involving John’s character.”
John will start filming with the Holby City team in the coming months and fans will see him on screen later this year.