Despite his decision to sit out the year due to his knee, the Hornets still traded Mashburn, along with Rodney Rogers, to the Philadelphia 76ers in exchange for forward Glenn Robinson on February 24, 2005. Mashburn was never able to recover from his chronic knee problems and never saw court time for Philadelphia. He was on the injured list for all of the 2004–05 season and the inactive list for 2005–06. On March 24, 2006, the 76ers waived Mashburn, who subsequently announced his retirement from the NBA. He had career averages of 19.1 points, 5.4 rebounds and 4.0 assists per game.