Warner was a standout at Pineville High School in Pineville, West Virginia, graduating in a class of only 90 students. He would lead Penn State in rushing in 1980, 1981, and 1982, and help the Nittany Lions capture their first national championship in the 1983 Sugar Bowl. When his collegiate career was over, he owned 42 Penn State records (his 3,398 career rushing yards is 2nd in school history, and his 18 100-yard rushing games remains a Penn State record). On October 30, 2010, Evan Royster surpassed Warner to take over the career rushing yards record. He was named an All-American twice, in 1981 and 1982.
Warner earned a Bachelor of Arts in speech communication from Penn State in 1983.