The Heroes veteran is thought to be joining the cast of the TNT crime drama created by former Walking Dead showrunner Frank Darabont, according to Deadline.
Ventimiglia will play a marine named Ned Stax who becomes a "fixer" for the mob.
The series is based on the John Buntin book L.A. Noir: The Struggle For The Soul Of America's Most Seductive City. Set in the 1940s and 1950s, it centers on the fight between the LAPD, led by Police Chief William Parker, and the crime organisation championed by the infamous mobster Mickey Cohen.
The Walking Dead's Jon Bernthal is reportedly in negotiations to play Los Angeles police officer Joe Teague.
Ventimiglia has started developing a new comedy pilot for FX focusing on a group of drone pilots in Nevada.
Darabont left The Walking Dead in July last year.