Johnson finished with 12 points and six assists for the Bruins (26-6, 14-2 OVC), who claimed the Ohio Valley Conference championship in the title game of the league's post-season tournament.
J.J. Mann added 18 points and grabbed seven rebounds for Belmont, which also reached the post-season each of the last two years while a member of the Atlantic Sun Conference.
The Racers (21-10, 10-6) got 23 points from Stacy Wilson.
Isaiah Canaan contributed 22 points, 10 assists and nine boards for Murray State, but also committed a costly late turnover that led to Johnson's game-winner.
Mathematician offers formula for finding the perfect Christmas tree
Wisconsin business offering 'therapeutic cuddling' forced to close