Kuhn died at St. Luke's Hospital in Jacksonville.
Kuhn was 44 when he became the game's youngest commissioner ever in 1969.
He presided over the dawn of free agency and the end of baseball's reserve system.
The reserve clause in the basic player contract was used by owners to bind players to their respective teams. It was overturned in 1972 after it was tested in court by St. Louis Cardinals outfielder Curt Flood.
Kuhn's tenure lasted until 1984.
Kuhn's support among owners eroded after the players' strike in 1981 when the players union gained strength and clout.