Pressey has appeared in 125 games with the Boston Celtics, averaging 3.1 points, and 2.9 assists in 14 minutes per game. Pressey was on the active list for Wednesday night's game in Milwaukee against the Bucks.
The undermanned Sixers are without center Joel Embiid for a second straight season because of a foot injury. Robert Covington went on the injury report this week with a sprained right knee, joining three other players.
Pressey could play right away for the Sixers, who started rookie T.J. McConnell at point guard against the Bucks.
Pressey is the son of former NBA player Paul Pressey.