Gatski was born in West Virginia to a coal-mining family. He played for three years on his local high school team before attending Marshall University, where he continued to play football. He joined the U.S. Army in 1942 and went to fight in World War II. Upon his return in 1945, he played in a couple of games at Auburn University in Alabama, before officials found out he had attended and played for Marshall, and took classes. After graduating, he tried out and made the roster for the Browns, a team under formation in the new AAFC thanks to Johnny Brickels, the former Huntington High School football coach who knew Paul Brown (Ed Ulinski of Marshall also tried out, played and later coached the Browns) after another former Marshall player, Sam Clagg, alerted Brickels to the two players. Gatski played as a linebacker and backup center for most of his first two years before earning a spot as the starting center. He retained that position as Cleveland continued to dominate the AAFC, going 47-4-2 and winning four championships before the league dissolved and the Browns, the San Francisco 49ers and Baltimore Colts were absorbed by the NFL in 1950. Gatski and the Browns won the 1950, 1954 and 1955 titles, losing in the title game in 1951-52-53. He retired after the 1957 season when he won an eighth title with the Detroit Lions, never having missed a game or practice in his career.