The freshman forward made the announcement in an Instagram video while accompanied by his mother.
The 6-foot-10 Isaac averaged 12.0 points and 7.8 rebounds for the Seminoles in 2016-17. He is ranked No. 5 on ESPN Insider Chad Ford's latest Big Board, and several NBA executives told ESPN that Isaac will likely be a lottery selection in June's draft.
ESPN's Jeff Goodman contributed to this report.