Otis was drafted by the New Orleans Saints in 1970. The following year, he was traded to the Kansas City Chiefs. However, Otis played the last six years of his nine-year NFL career with the St. Louis Cardinals. Otis's most successful year as a professional was in 1975, when he rushed for an NFC-leading 1,076 yards and was selected to the Pro Bowl. Otis beat Minnesota's Chuck Foreman by 6 yards, thus preventing Foreman (who led the NFC in touchdowns and receptions that year) from achieving a rare Triple Crown.
Otis's father, Dr. James John Otis, had been the roommate and best friend of Ohio Statehead coachWoody Hayes when both men were members of the Sigma Chifraternity of Denison University in the 1930s. To avoid any appearance of impropriety, Hayes broke off all social contact with the elder Otis during the son's college career. Dr. Otis lived and operated a medical practice in Celina, Ohio.