O'Keeffe had stipulated that the collection never be sold. A legal battle over the issue lasted more than a decade.
Fisk had said the school might have to close if it didn't sell the stake to the museum, built by Wal-Mart heiress Alice Walton.
Current Fisk President Hazel O'Leary, who was energy secretary in the Clinton administration, had planned to retire Dec. 31 but the university said in its statement Wednesday night she would delay her departure to ensure a smooth transition.
Williams said he will share his plans for Fisk's future once he gets on campus and talks with its faculty and administrators, but right now is just preparing to transition.
"I'm looking to living in the Nashville community and working with that community to make sure that Fisk can be all that it can be," he said.
According to the Grand Valley State University website, Williams has worked as a corporate and tax attorney.
He earned a bachelor's degree in accounting from North Carolina Central University, a MBA in accounting at the University of Wisconsin, and a Ph.D. in accounting at the University of Georgia.
He got his law degrees from Georgetown University Law Center.