Kevin Garnett Is Retiring

Kevin Garnett has decided to call it quits after 21 seasons in the NBA.

K.G. hit up Instagram ... and posted an emotional video saying "farewell" to his fans.

The 5th overall pick of the 1995 Draft, Garnett spent most of his career with the Wolves, and was the league MVP in 2004. He won an NBA title as a member of the Boston Celtics in 2008.

The Big Ticket was a 15 time All-Star ... and is a shoo-in for the Pro Basketball Hall of Fame.

Hardware aside, K.G. will go down as one of the best trash-talkers of all time ... after famous on-court (and off-court) feuds with Dwight Howard and Carmelo Anthony.