The player who hit the most home runs in a single season played how many seasons of Major League Baseball ?
50 home run club:  Barry Bonds hit the most home runs to join the club, collecting 73 in 2001. Barry Bonds: Barry Lamar Bonds (born July 24, 1964) is an American former professional baseball left fielder who played 22 seasons in Major League Baseball (MLB) with the Pittsburgh Pirates and San Francisco Giants.
22 seasons