The Cardinals (13-11, 7-5) moved a half-game ahead of Central Michigan, which hosts Toledo on Sunday. Ball State and Central Michigan meet Wednesday in Muncie, Ind.
Ball State overcame a 30-point, 10-rebound performance by Xavier Silas, who was the only Northern Illinois player in double figures. The Huskies (8-16, 4-8) have lost eight straight games in conference play.
Randy Davis had 20 points, Jarrod Jones 16 and Pierre Sneed 11 for Ball State, which avenged a 62-48 loss to Northern Illinois earlier this season.
Davis hit two free throws with 1:06 left to put the Cardinals on top for good, 66-64. On the ensuing possession, Darion Anderson missed two free throws for Northern Illinois.