Hopkins, who is ranked No. 32 in the ESPN 100, originally committed to the Cardinals in November.
"Every time I've gone, the coaches have been genuine and they had a great vision for me that I loved," Hopkins told ESPN at the time. "I felt completely comfortable with the coaching staff."
Hopkins, a versatile 6-foot-6 forward from Fenwick High School in Illinois, was the headliner in a strong early class for coach Chris Mack and the Cardinals. Despite his decommitment, Louisville still has three pledges in 2021: ESPN 100 point guard Bobby Pettiford, talented junior college guard El Ellis and four-star forward Eric Van Der Heijden.