He began his career as a child actor and achieved a career breakthrough with his supporting role as Landry Clarke in the NBC drama series Friday Night Lights (2006–2011).
He subsequently portrayed Todd Alquist in season 5 of the AMC crime drama series Breaking Bad (2012–2013) and its sequel film El Camino: A Breaking Bad Movie (2019).
For his role as Ed Blumquist in season 2 of the FX anthology series Fargo (2015), he received his first Primetime Emmy Award nomination and won a Critics' Choice Television Award.
He received a second Emmy nomination for his portrayal of Robert Daly in "USS Callister", an episode of the Netflix anthology series Black Mirror (2017).
Plemons began a relationship with his Fargo co-star Kirsten Dunst in 2016.They got engaged in 2017.