Campbell grew up in Ohio and briefly attended the University of Pittsburgh before transferring to Mount Union, where he played defensive line.

[5] After college, Campbell stayed within Ohio and took a job as a graduate assistant at Bowling Green State University from 2003 to 2004.

This move reunited him with head coach Tim Beckman, defensive coordinator at Bowling Green during Campbell's first stint there.

Toledo made Campbell the permanent head coach at the end of 2011 when Beckman departed for the University of Illinois.

[2] Reportedly Campbell passed on a chance to serve on Urban Meyer's staff at Ohio State University.

[9] Iowa State University named Campbell its head coach on November 29, 2015, his 36th birthday, replacing the fired Paul Rhoads.

[11] In his second year, Campbell led Iowa State to an 8–5 season that included wins against #3 Oklahoma and #4 TCU.

[13][14] On September 28, 2024, Campbell passed Dan McCarney to become the winningest coach in school history with a shutout victory over Houston.

In the summer of 2022, Campbell served as the head coach of the Gilbert 6th grade softball team.