In the special, which will be released on November 1 to mark the ITV soap's 50th anniversary, Curly Watts (Kennedy) will be seen as the boss of several hotels, PA reports.
The storyline will see him offer his old boss Reg Holdsworth (Morley) a job hosting a medieval weekend at a stately home called Tatlock Towers.
Current Corrie stars including Helen Flanagan (Rosie Webster) and Ryan Thomas (Jason Grimshaw) will also feature.
Rosie is hired as a serving wench under false pretences by Reg. Excited, she drags Jason along as she believes she could become the new face of Strumpet Ale. However, while working, she meets a plastic surgeon who suggests that she needs some work done, whether she wants it or not.
Flanagan teased: "The script looks like loads of fun - you'll be seeing Rosie at her most outrageous best!"
Also appearing on the DVD, which will be available to download, will be Mary Taylor (Pattie Clare), on whom Reg sets his sights.
Kennedy admitted that he is "absolutely delighted" to reprise the role and praised the idea to reunite Curly and Reg.
"To be back with Ken Morley is something I think a lot of fans have been waiting for - as a double act, Curly and Reg were very, very funny," he said.
Morley added: "I can only echo everything Kevin has said except add that both Kevin and I are fatter, older and not necessarily wiser!
"We look forward to continuing with the mayhem we first dropped on the nation all those years ago."
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