His announcement came Monday through a unique Instagram post:
The 37-year-old has played for nine different organizations since being selected in the second round of the 2002 draft. His final stop came with the Golden State Warriors, who he joined after being waived by the Sacramento Kings last February.
He provided much-needed depth for the Warriors, averaging 5.7 points and 4.6 rebounds per game in 20 appearances during the regular season. Although he made a minimal impact in the postseason, he still earned his first championship on a team that went 16-1 in the playoffs en route to a title.
Barnes has had an interesting career that often saw him contribute more on the court than his statistics would indicate. He lasted a long time in the league despite never scoring more than 11 PPG in a season and only four times reaching double figures.
Still, Forbes listed him as the most underpaid player in the NBA in 2013.
Although he wasn't always the most popular player around the league, his contributions helped numerous teams while earning him consistent playing time on top contenders.
Barnes didn't plan on retiring at the end of last season, saying in May, "I feel like I've got another year or two left in the tank," per Connor Letourneau of the San Francisco Chronicle.
Unable to find a new landing spot, however, Barnes will move on to the next phase of his career.