On top 39-34 at halftime, Eastern Kentucky opened the second half on a 15-6 run to go up 54-40 with 14:37 left to play.
The Colonels took their biggest lead of the game, 65-46, on Johnson's layup with 9:01 remaining.
Brian Williams' 3-pointer cut Jacksonville State's deficit to 71-67 with just under 2 minutes to play, but the Gamecocks failed to score another point.
Eastern Kentucky shot 53.6 percent (15 of 28), while Jacksonville State shot 42.3 percent (11 of 26), in the second half.
Tarvin Gaines led the Gamecocks (15-10, 7-7) with 21 points.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.
|Southeast Missouri State||2-14||8||5-24|