After serving for twelve years in Lutheran middle and high schools in Illinois and Wisconsin, Bull began his higher education career in 2006 at Concordia University Wisconsin, serving as a professor of education, Chief Innovation Officer, and Vice Provost of Curriculum and Academic Innovation.

In 2012, he was named a Thrivent Fellow, a fellowship dedicated to equipping current and emerging higher education leaders. That same year, he was granted the Wagner Distance Education Award.

In 2016, Bull became the Jonathan D. Harber Fellow in Education and Entrepreneurship at Wesleyan University in Middletown, Connecticut, where he taught Social Entrepreneurship in Education and during which he completed the manuscript for Adventures in Self-Directed Learning.

In 2018, Bull became president of Goddard College, a low-residency alternative and experimental college. Bull accepted the job months after it was placed on probation by the New England Commission of Higher Education over concerns regarding institutional resources and organization and governance, with growing questions about whether the college would survive. In September, 2020, Goddard was removed from probation and its accreditation was renewed.

On December 1, 2020, Concordia University Nebraska announced Bull as the president-elect, scheduled to transition from Goddard College to Concordia University Nebraska in August 2021.

Bull's writing and scholarship focuses on educational innovation, contemporary issues in education, futures in education, and religious education. Bull attended Metro East Lutheran High School in Edwardsville, Illinois.He went on to earn a Bachelor of Arts in history and education from Concordia University Wisconsin in 1993. He completed a Master of Arts in Curriculum and Instruction from Concordia University Chicago, a Master of Liberal Studies from the University of Wisconsin-Milwaukee, and a Doctorate of Education in instructional technology from Northern Illinois University.