Nick De Leon also scored to help United (3-2-3) stretch their unbeaten run to six matches. United moved past New York into second place in the Eastern Conference, nine points behind first-place Kansas City.
Thierry Henry scored a late consolation goal for the Red Bulls (3-3-1), who suffered their first loss in five matches.
The Red Bulls struggled defensively without fullback Rafa Marquez, who served the first of a three-match suspension for violent conduct displayed in last weekend’s 2-2 draw against San Jose.
Pointius scored twice before halftime before adding his team-lead tying fourth goal of the season just beyond the midway point of the second half.
Pontius got D.C. on the board in eighth minute by dispossessing Henry near midfield, pushing forward and smashing a 25-yard shot past goalkeeper Ryan Meara. Pontius doubled the lead in the 32nd minute after Maicon Santos’ cross redirected off defender Connor Lade and into position for a point-blank shot.
Pontius made it 4-0 in 69th minute with a breakaway effort before Henry scored on a 72nd-minute free kick.
United have scored four goals in two of its wins this season, and have given up one goal or less in seven of eight games.
They’ve also scored four or more goals nine times in the teams’ all-time regular season series, which D.C. leads 31-19-7.