Leighton and another original Melrose alumni, Thomas Calabro, are on board for the new version of the classic US soap, TV Guide reports.
The actress played scheming Sydney Andrews until 1997 when her character was killed off in a plot which is addressed in the update.
"We're chipping away at it," Leighton said. "There is an explanation that I think is going to be slowly unravelled."
It is understood that Sydney will sleep with the son of Calabro’s Dr. Michael Mancini - who she manipulated into marriage during the show's first run.
She added: "Sydney has most likely always maintained some sort of relationship with Michael. It's been complicated, and that's not going to change."
Following Heather Locklear's decision to pass on the opportunity to reprise her role as the residence’s landlady Amanda Woodward, Sydney will collect the rent from the Los Angeles apartment complex's occupants.
Melrose Place originally aired for seven seasons from 1992 to 1999.