At Notre Dame, Rockne was educated as a chemist and he graduated in 1914 with a degree in pharmacy. After graduating, he was the laboratory assistant to noted polymer chemist Julius Arthur Nieuwland at Notre Dame and helped out with the football team, but rejected further work in chemistry after receiving an offer to coach football. In 1914, he was recruited by Peggy Parratt to play for the Akron Indians. There Parratt had Rockne playing both end and halfback and teamed with him on several successful forward pass plays during their title drive. Knute wound up in Massillon, Ohio, in 1915 along with former Notre Dame teammate Dorais to play with the professional Massillon Tigers. Rockne and Dorais brought the forward pass to professional football from 1915 to 1917 when they led the Tigers to the championship in 1915. Pro Football in the Days of Rockne by Emil Klosinski maintains the worst loss ever suffered by Rockne was in 1917. He coached the "South Bend Jolly Fellows Club" when they lost 40–0 to the Toledo Maroons.
Rockne met Bonnie Gwendoline Skiles (1891–1956) of Kenton, Ohio, an avid gardener, while the two were employed at Cedar Point. Bonnie was the daughter of George Skiles and Huldah Dry. The two married at Sts. Peter and Paul Catholic Church in Sandusky, Ohio, on July 14, 1914, with Father William F. Murphy officiating and Gus Dorais as best man. They had four children: Knute Lars Jr., William Dorias, Mary Jeane and John Vincent. Rockne converted from the Lutheran to the Roman Catholic faith on November 20, 1925. The Rev. Vincent Mooney, C.S.C., baptized Rockne in the Log Chapel on Notre Dame's campus.