Johnie Cooks played college football at Mississippi State where he earned four letters, and earned a degree in physical education. During his college career, he amassed 373 tackles, 241 of those unassisted. During his junior year, he recorded a career high 24 tackles in a game against Auburn. He was also the defensive MVP in the 1981 Hall of Fame Bowl.
Cooks was the second overall draft choice, selected in the first round of the 1982 NFL Draft by the Baltimore Colts. He started only two games in his rookie season, but by the end of the season, he had 63 tackles, one sack, and one fumble recovery. In 1983, he was moved to the outside linebacker position, this time recording 67 tackles that year. He also had a 52-yard fumble return in overtime against the New England Patriots that won the game for Baltimore. After having only 5 quarterback sacks in 1983, Cooks recorded 11 1/2, which led the Colts. His best game occurred against the Raiders, when he sacked the quarterback Jim Plunkett 4 times.
In 1988 Cooks was released by the Colts and was picked up by the New York Giants. After playing for years on mediocre Colts teams Cooks won a Super Bowl title when the Giants defeated the Buffalo Bills. He was released by the Giants in 1991 and signed with the Cleveland Browns in 1992. Nagging injuries caused Cooks to retire after the 1992 season.