Agent Mark Bartelstein announced the move Friday.
Brown will be reunited with Sixers coach Doug Collins. Collins was Brown's first coach in Washington in 2001. Brown has averaged 6.8 points and 5.6 rebounds over an 11-year career.
The well-traveled Brown was the No. 1 overall pick out of high school in the 2001 draft by the Washington Wizards.
Bartelstein said one reason Brown was eager to join the Sixers was because Collins was like a "father figure" to the center.
"Kwame and Doug have a relationship that I think really has grown over the years," Bartelstein said. "It's a great fit."
Brown signed a $7 million, one-year deal with Golden State before last season. But he played in only nine games and averaged 6.3 points and 6.3 rebounds in 20.8 minutes before needing season-ending surgery on his chest muscle.
The 30-year-old Brown is set to play for his seventh team. He will join a frontcourt that includes Spencer Hawes, Thaddeus Young, Lavoy Allen, Nik Vucevic and rookie Arnett Moultrie. The Sixers waived veteran forward Elton Brand this week.
"It gives Kwame a chance to play an integral role on a playoff team," Bartelstein said.
Brown never lived up to his No. 1 billing after Michael Jordan picked him out of high school. Only once has he averaged double digits in points over a full season and, even in his limited minutes, the 6-foot-11 center failed to block a shot last season.
Brown played four seasons with the Wizards before bouncing around to the Lakers, Memphis, Detroit, Charlotte and the Warriors.
The Sixers also this week acquired forward Dorrell Wright from the Warriors and signed free-agent guard Nick Young to a one-year contract.