An 86th-minute winner from Russell Canouse lifted DC to a hard-fought win at Audi Field.
With the victory, Ben Olsen's men moved into sixth spot in the Eastern Conference, sitting a point ahead of Montreal Impact.
Wayne Rooney, who missed an excellent early chance for DC, played a role in the winner.
The former England and Manchester United star drifted in a set-piece, which Canouse eventually headed in after initially hitting the crossbar with a volley.
Elsewhere, Colorado Rapids ended a seven-game losing streak with a 2-0 win over Minnesota United, with both teams finishing the encounter with 10 men after an ugly encounter on the sidelines in the wake of the Rapids' second goal.
DC's win meant New England's play-off chances were ended, but the Revolution recorded a 2-0 victory against Orlando City.