The 38-year-old actor - who has been linked to the US crime drama since July - has now confirmed he will be portraying one of the lead characters, Detective Martin Eric "Marty" Hart or Detective Rustin Spencer "Rust" Cohle, previously played by Matthew McConaughey and Woody Harrelson.
The Irish-born star confessed he was "so excited" about the project and is thrilled that filming is taking place around Los Angeles so he can be close to his children, Henry, 4 and James,11.
He told Ireland's Sunday World: "I'm doing the second series. I'm so excited.
"I know it will be eight episodes and take around four or five months to shoot.
"I know very little about it, but we're shooting in the environs of Los Angeles which is great. It means I get to stay at home and see the kids."
Although further cast details for the second season - which is set to air in summer 2015 - are yet to be released, 'Wedding Crashers' star Vince Vaughan and 'Battleship' actor Taylor Kitsch are also rumored to be involved in the next installment of the HBO show.
In addition to new cast members, creator Nic Pizzolato previously revealed that the second season of the Emmy Award-winning drama will be about "hard women, bad men and the secret occult history of the United States transportation system".
Here's season one's trailer: