Matt Kelly Barnes (born March 9, 1980 in Santa Clara, California) is an American professional basketball player currently playing for the Orlando Magic of the National Basketball Association.

After a college career at UCLA, Barnes was a second-round draft choice of the Memphis Grizzlies in the 2002 NBA Draft. He was then traded that summer along with Nick Anderson to the Cleveland Cavaliers for Wesley Person, but was cut that October. He has since played for the Los Angeles Clippers, the Sacramento Kings, the New York Knicks the Philadelphia 76ers, the Golden State Warriors, and the Phoenix Suns averaging 6.1 points per game.

He was traded by the Kings halfway through the 2004–05 season along with Chris Webber to the 76ers, in exchange for Kenny Thomas, Corliss Williamson and Brian Skinner, though he never suited up for a game with them due to knee tendinitis. He was waived and then signed a free agent contract with the New York Knicks in the 2005 NBA offseason. He was waived by the Knicks during the 2005–06 season after playing six games. He was then claimed by the 76ers to serve a second stint in Philadelphia, where he finished out the season.

Barnes signed with the Golden State Warriors before their first day of training camp in October 2006, and has effectively raised his status in the league since joining the team. With struggling forward Mike Dunleavy, Jr. placed on the bench, Barnes was given more playing time by coach Don Nelson. On December 26, 2006, he hit 7 three-point field goals to tie a Warriors franchise record.The record was broken later that season by Jason Richardson, who hit 8 three-pointers on March 29, 2007. Barnes, a high-school All-American wide receiver, says that if he had not been signed by the Warriors he would have tried out for the NFL.

Before signing with Golden State, Barnes had only made 10 three-pointers in his career. In the 2006–07 season, he made 106. After joining Golden State, Matt's offense improved impressively, from 3 points a game in Philadelphia to 9.8, appearing in 76 games. He also added a strong 2007 post-season, with 11.1 ppg and 5.7 rpg in eleven playoff games and helped the #8 seed Warriors take down the #1 seed Mavericks in the 2007 playoffs.

On August 6, 2007, Barnes returned to the Warriors under a one-year contract.

Barnes, along with teammates Stephen Jackson and Baron Davis, served as a Warriors team captain for the 2007–08 season. He was not expected to return for the 2008–09 season.

On July 22, 2008, Barnes signed a one-year contract with the Phoenix Suns.

On November 14, 2008, Barnes was suspended for two games without pay for his role in a fight after a non-call foul on Rafer Alston.

On July 23, 2009, Barnes signed a two-year deal with the Orlando Magic. Although he is able to opt out of his deal after the first year, Barnes stated that he would like to remain in Orlando.