The pair's wedding is expected to air on screen in December to coincide with the Weatherfield soap's 50th anniversary celebrations.
According to the Daily Star, the new storyline will begin when former call girl Leanne, played by Jane Danson, pops the question to her partner at the Rovers Return.
After dropping down on one knee in front of fellow pub patrons, Leanne reportedly says: "I know I'm a nightmare and can be a stroppy cow at times, but Peter, will you do me the immense honour of marrying me?"
Recovering alcoholic Peter (Chris Gascoyne) apparently replies by saying: "I will if you will."
Coronation Street's bosses have so far revealed few details about the programme's anniversary plans, though series producer Kim Crowther recently teased that it would be based around a "big event".
Speaking to DS earlier this month, she commented: "It's just that the event may change! This is the ongoing discussion - it's still being debated and would have to be part of the story which is building."
Leanne has been involved in an on-off relationship with Peter since he returned to Weatherfield in November 2008.