After graduating college with a
bachelor's and
master's degree, Cullivan started a coaching career, being named assistant at
Fulton High School in
Kentucky in 1949. After two years there, he returned to his
alma mater Murray State as an assistant coach. When head coach
Fred Faurot resigned in 1956, Cullivan was named the replacement. He finished his first season as head with a 6–4 record, with three of the four losses coming by one point. His team compiled a 3–5–1 record in
1957, a 3–7 record in
1958, and a winless 0–10 in the following, leading to his firing in January 1960. After leaving Murray State, Cullivan took a year off from coaching to work on a
doctorate from
University of Indiana. In 1961, he was hired by Eastern Kentucky State College (now
Eastern Kentucky University) as
defensive coordinator. He resigned in 1964 to join
Appalachian State University. He served as
backfield coach for two years, and was associate professor of health and physical education. After two seasons with Appalachian State, he was signed by Grove High School in 1966 as defensive coordinator and head coach. While there, he coached his three sons, Jim, Bill, and Pat.
Henry County High School, where he served for the next two years as their first football coach. He was promoted to head coach in 1980, and posted a 65–21 football record in nine seasons. He helped them achieve two undefeated years and seven playoff berths. After a stint with them, he had a short stay with a team in the
United Professional Football League (UPFL) before retiring. ==Later life and death==