The 38-year-old Irish actor will board Nic Pizzolato's acclaimed series, which starred Matthew McConaughey and Woody Harrelson in its first outing, reported Variety.
"I think the people we will cast will be well-known names. But that wasn't our ambition (in season 1)," HBO president Michael Lombardo said.
It is rumoured that Farrell will be joined by a female co-star, though Nic Pizzolatto confirmed that the show will feature four lead roles.
"They didn't exist until I created them, then in their creation I developed a personal attachment to them," Pizzolatto said of his new characters.