"We're thrilled that the NCAA has made this decision and given a fine young man the opportunity to pursue his dreams," head coach Mike Anderson said in a statement. "Rasheem has always done things the right way and we're very excited and appreciative that the NCAA has ruled in his favor."
Dunn spent his first two collegiate seasons with St. Francis Brooklyn, averaging 14.3 points, 5.4 rebounds, and two assists across 60 appearances.
He transferred to Cleveland State following his sophomore year but didn't appear in any games for the Vikings during the 2018-19 campaign. Dunn transferred to St. John's at season's end.
"I appreciate all the support I have received from St. John's," Dunn said in a statement. "I couldn't ask for a better opportunity. It was worth the wait."
St. John's went 21-13 last season but struggled in Big East play, going just 8-10. Still, the Red Storm managed to make the NCAA Tournament, falling to Arizona State in the First Four.
Dunn will make his St. John's debut Saturday against Vermont.
The Red Storm are off to a 3-0 start this season.