Johnson was 10 of 11 from the floor as the freshman collected his fourth double-double. Chris Harrison-Docks added 15 points and Marlon Hunter 11 for Western Kentucky (5-4), which won its sixth straight road game over two seasons.
Leading by seven at halftime, the Hilltoppers opened the second half on an 18-5 run to go up 55-35 with 11:44 to go. The lead never went under 12 with a pair of baskets by Johnson making it 75-46 with 53 seconds remaining.
Though only 210 miles apart, this was only the sixth meeting between the schools and just the second in 74 seasons since 1941-42. The other was in 2009.