The Big Unit, an overpowering lefty who last June became the 24th pitcher in big league history to win 300 games, made the expected announcement Tuesday on a conference call.
A five-time Cy Young Award winner, the 46-year-old Johnson accomplished just about everything in his remarkable career that a player hopes for in baseball.
He owns a World Series ring and co-MVP honors, and was a 10-time All-Star. He threw two no-hitters, including a perfect game, and ranks second on the career strikeout list.
The 6-foot-10 Johnson finishes with a career record of 303-166 and 4,875 strikeouts in 4,135 1-3 innings.