Washington won for the fourth time in its last five games while the Sixers have dropped seven of their last eight.
The Wizards had a 10-2 run over 3 1/2 minutes later in the first half to fashion a 25-16 lead. The Washington lead was six at the end of the first period and 61-51 at halftime. The Wizards pulled out to a 100-79 advantage midway through the fourth quarter.
Only a very late 3-pointer from Hollis Thomason got the Sixers within double figures by game's end.
Beal finished with eight assists and seven rebounds to support his 22-point scoring. Marcin Gortat chipped in a 19-point, 11-rebound effort while Kevin Seraphin scored 26 points and John Wall 14 for Washington.
Michael Carter-Williams, connecting on 13-of-22 shots from the floor, led all scorers with 31 points. Thaddeus Young added 18 points and Spencer Hayes had a double-double with 11 points and 16 rebounds.