In his one and only season as the coordinator, Nolan led a defense that was one of the worst in rushing and points allowed per game. His defense allowed the most points in team history with 473.
He joined the Cowboys staff after Mike McCarthy was named head coach in 2019.
Defensive line coach Jim Tomsula was also reportedly fired.
McCarthy released a statement saying, “I am appreciative of my relationships with both Mike and Jim, and I am grateful for the contributions that both of them made to our team under difficult circumstances in 2020. These are never easy decisions to make, and we wish them, and their families, the very best in the future.