The Wizards staged a fourth-quarter rally that saw them open the period on an 18-3 run, but they eventually lost for the seventh straight time to open the season.
Washington is now the lone winless team in the NBA, Detroit having captured its first victory earlier in the evening in Philadelphia.
A jump hook shot by Kevin Seraphin brought the Wizards within three points with 1:56 to play, after which Dallas missed two shots, grabbed two offensive rebounds and then turned the ball over when Darren Collision made a bad pass.
Washington's Jannero Pargo launched a 3-point attempt with 55 seconds left that would have tied it, but it bounced off the rim.
The Mavericks boosted their lead to six points at the foul line before Cartier Martin kept Washington's hopes alive with a 3-pointer.
That came with 21 seconds remaining, but Kaman ended the Wizards' chances when he made a hook shot while being fouled. His free throw brought about the final score.
O.J. Mayo scored 25 for the Mavericks, who ended a three-game skid, and Kaman had 23.
Jordan Crawford led the Wizards with 21.