Gullett attended McKell High School in South Shore, Kentucky where he was an outstanding three sports athlete in baseball, football, and basketball. As a high school pitcher, he once tossed a perfect game—including striking out 20 of the 21 hitters he faced. Gullett excelled as a high school football player as well once scoring 72 points in a single game. He ran for 11 touchdowns and kicked 6 extra points. Don was named all state in three sports his senior year (baseball, football, basketball). Gullett's legacy is remembered in a memorial on the courthouse lawn in Greenup County, Kentucky that declares that "This is Don Gullett Country."
Gullett played for the Reds from 1970 through the 1976 season. In November of that year, as a free agent, he signed with the New York Yankees. He enjoyed a 14–4 season with the Yankees in 1977, but shoulder problems in 1978 signalled the end of his career.
During a nine-year career, Gullett accumulated 109 wins and posted a 3.11 Earned Run Average (ERA) and tallied 921 strikeouts. Playing for only nine seasons, Gullett was a member of six World Series teams (1970, 72, 75, 76, 77, 78), including four consecutive World Champions ('75 and '76 Reds, and '77 and '78 Yankees).