From 2001 through 2019, Harrell had various coaching positions as an assistant coach at Western Carolina, McDowell High School, Fuquay-Varina High School, Franklin High School, Lenoir-Rhyne, The Citadel, and Kennesaw State.[1][2][3] On January 28, 2020, Harrell was hired by the East Carolina Pirates as the team's defensive coordinator and linebackers coach.[4] On October 20, 2024, After former East Carolina head coach Mike Houston was fired, Harrell was named the team's interim head coach.[5][6] Following a 4–0 start, East Carolina made Harrell the permanent head coach.[7]