He was educated at Cornell University, where he was a guard on the football team for three years, heavyweight boxing champion one year, and on the track team two years.
Warner graduated with a LL. B. degree in 1894.
After graduating he was admitted to the New York State bar the same year, but a career in athletics appealed to him more strongly than legal practice. He began coaching the football team of the University of Georgia in 1895, receiving only $3. 50 a week for a ten-week session. In 1896 his Georgia team was unbeaten and untied, and Warner was engaged to coach at Cornell the next two years. In 1899 he became coach at Carlisle Indian School, Carlisle, Pennsylvania. There, except for a short interval, he remained 16 yeas and made a national reputation. His teams sparked by the great Jim Thorpe and several other All-America players, toured the country, defeating most of the strong university elevens. In 1915 Warner went to the University of Pittsburgh, where in the next nine years he developed three undefeated teams; two tied for the national championship, and one won it. He then coached at Stanford University from 1924 through 1932, turning out three Rose Bowl teams. From 1933 through 1938 he was at Temple University, and in the two following years he was advisory coach at San Jose (California) State College. Next to Amos Alonzo Stagg, "Pop" Warner had the longest continuous coaching career in American football, a total of 46 years. He originated the crouch start, the single and double wing back formations, and the clipping block. Warner wrote Football for Coaches and Players (1927).