Season 1 is to wrap May 20. Its second season is to begin airing in 2014.
Aden Young stars in the show, which Sundance describes as "a haunting story of a man released from prison after spending nearly two decades on death row." The cast also includes Abigail Spencer, Luke Kirby and J. Smith Cameron.
"The response to 'Rectify' has been incredible," Sarah Barnett, Sundance Channel's president and general manager, said in a statement.
"We feel as though this story has tapped into something truly unique, with both critics and audiences using their platforms to share such strong, personal reactions to this very distinctive TV series. There's so much drama and character that's been set up in the first season, it will be electrifying to see where 'Rectify' goes in Season 2."