Johnson becomes Memphis coach Josh Pastner's first verbal commitment since it was announced that the Tigers would be jumping from Conference USA to the Big East, in all sports, beginning in 2013.
The 6-foot-3, 200-pound Johnson graduated from Dunbar (Dayton, Ohio) in 2010 and was rated a 3-star prospect. Johnson enrolled at Chipola College (Marianna, Fla.) before being dismissed. He landed at GCCC last year.
Johnson took official visits to Memphis and Kansas.
"He's not a true point guard, but you can play him there," said Scout.com national recruiting analyst Brian Snow. "He's a great passer and a good athlete. He can really do it all."
Johnson was recruited likely as the closest thing to a replacement for sophomore guard Will Barton, who could head to the NBA after this season.
"He's different than Will," Snow said. "Geron is more of a distributor while Will is a scorer. (Johnson) isn't as talented overall, but he's very good. There aren't many guys this good who are still available. There's no question he has the ability to be an impact guy from day one."
Snow said that, from the last time he saw Johnson in game action, he could stand to improve his defense and perimeter show.