Drexel (13-4, 5-2 Colonial Athletic Association) trailed for most of the first half but took command of the game with a 17-0 run spread over both periods.
Northeastern led 25-23 with 3:31 remaining in the first half, but Drexel scored the final nine points of the first half for a 32-25 margin and the first eight points of the second half, capped by Chaz Crawford's two free throws, for a 40-25 lead with 14:58 remaining.
Mejia hit back-to-back 3-pointers to extend the Dragons' lead to 51-30 with 10:30 remaining. Crawford grabbed 11 rebounds for Drexel and has had double-digit rebound totals in six of the last seven games.
Northeastern scored only 16 points and shot 27.3 percent from the floor in the second half. The Huskies also committed 18 turnovers, including 12 as a result of steals, which Drexel converted into 24 points. The Dragons had only nine turnovers.
Drexel shot 55.1 percent from the field for the game and outscored Northeastern in the paint 36-14. Bashir Mason hit a jumper to cap a 10-2 run with 4:45 left in the first half that gave Drexel its first lead of the game, 23-21.