
In 1923, shortly after graduation from UC Berkeley, Knox accepted a position on the staff of Phoenix Union High School. Soon after, he met his wife Lois Wynne. The couple moved to Los Angeles in 1926, where Knox began his studies at USC.
With his doctorate in hand, Knox moved to the District of Columbia to accept a position on the staff of Howard University in 1931. (In the 1940s and 50s, Dr. Knox served as an adjunct professor at the American University, an adjunct lecturer at Yale University, and as a member of the Evaluation Committee of the Middle States Association of Colleges and Secondary Schools, while retaining full professor status at Howard.)
By 1955, Knox was appointed to the President's White House Conference on Education. A decade later, he began work as a consultant to both the Peace Corps and the U.S. Commission on Civil Rights. That was not all. In the tradition of his philopshical and academic focus of promoting civil rights in education, Knox worked alongside Thurgood Marshall in the campaign that led to the desegregation of the schools in the District of Columbia and also served as the Chairman of Education for the NAACP from 1945 to 1962 
In 1967, Knox ended his tenure at Howard University
and retired in Los Angeles, where he served as Professor Emeritus at the University of Southern California and the University of California Los Angeles until his death in 1975.
During his lifetime, Knox published several studies on the philosophy of education. His Ph.D. disseration dealt with the trend of philosophical doctrines in their relation to African-American youth in the United States.
Dr. Knox's contemporaries, colleagues, and close friends included Nobel Prize winner Ralph Bunche, United States Supreme Court Justice Thurgood Marshall, as well as famed California architect Paul Williams, and civil rights leader H. Claude Hudson