In 2008, Porter was cast as Lettie Mae Thornton, mother to Rutina Wesley's Tara Thorton, in the HBO drama series, True Blood. She was promoted to series regular in seventh and final season of show. In 2012, she guest starred in an episode of Grey's Anatomy. From 2012 to 2014, she also had a recurring role on the HBO series The Newsroom playing Kendra James. In 2014, she began appearing in a recurring role as Indra in the CW post-apocalyptic drama, The 100. Porter also starred in two unsold drama pilots for ABC, Doubt in 2013, and The Jury in 2016. In 2016, she played Pearly Mae during first season of WGN America period drama Underground. Later that year, Porter was cast as Lee Harris in the FX anthology series American Horror Story: Roanoke, after previously appearing as a minor character in American Horror Story: Murder House in 2011. For her performance in Roanoke, she received critical acclaim and was nominated for a Saturn Award for Best Supporting Actress on Television. She later portrayed Beverly Hope in American Horror Story: Cult where she received similar praise from critics and received a second Saturn Award nomination, as well as a Primetime Emmy Award nomination for Outstanding Supporting Actress in a Limited Series or Movie. She was later promoted to series regular for American Horror Story’s eight season entitled Apocalypse. In Feb 2020, Ryan Murphy announced that she will return for American Horror Story in its tenth season in another main role.