Knicks general manager Glen Grunwald made the announcement Tuesday, one day after the team released Solomon Jones.
The 6-foot-6 Richardson has career averages of 10.3 points on 39.8 percent shooting from the field and 35.5-percent shooting from three-point range. He has averaged 4.7 rebounds and 1.5 assists over 26.5 minutes in 12 seasons with the Clippers, Suns, Knicks, Heat and Magic. He has appeared in 31 postseason games (21 starts), averaging 8.5 points and 4.3 rebounds over 28.5 minutes.
Richardson has not played in the NBA since the 2011-12 season with Orlando. He spent four seasons (2005-09) with the Knicks, averaging 9.7 points and 5.0 rebounds.