Johnson announced the change in a social media post Monday. The 6-foot-6 Johnson graduated in December from Tennessee and was set to join ETSU under Steve Forbes, who later left to take over the Demon Deacons program.
In a statement, Johnson said he had "a great relationship" with Forbes and that he met with his family to discuss plans for his final college season after Forbes' departure.
Johnson played in 31 games last season, starting two, for the Volunteers. He averaged 3.5 points and 2.0 rebounds in 15.7 minutes per game.
The move marks a return to North Carolina for Johnson. His hometown is Durham, and he played in high school at Wesleyan Christian Academy in High Point, roughly 25 miles from the Wake Forest campus in Winston-Salem.
Johnson is the second player this month to follow Forbes from ETSU to Wake Forest. Last week, the Demon Deacons announced the addition of transfer Daivien Williamson after he had played his first two seasons under Forbes with the Buccaneers.