Dwight Howard had 17 points, 12 rebounds and three blocked shots for the Magic, who have won three straight and five of their last six games.
Orlando, which has clinched a playoff berth, holds the eighth seed in the Eastern Conference.
Jamison was three points shy of a career high and had nine rebounds. Jarvis Hayes added 15 points for the Wizards, who have lost nine of their last 11 games.
Washington fell into a tie with New Jersey for the seventh seed in the Eastern Conference playoffs. The Wizards plays at Indiana on Wednesday, while the Nets will host Chicago.