Grant announced Pierre's intentions Wednesday.
Pierre, from Orlando, Florida, played 41 games with the Cougars. He averaged 1.0 points, 1.5 rebounds and less than one block a game during his time at Charleston. Pierre's best game was against Texas A&M when he scored eight points at the Puerto Rico Tip-Off tournament this past season.
Grant called Pierre a ''terrific young man'' and wished him well with his career.
Earlier this offseason, 7-2 center David Wishon also transferred after playing just 10 games last season.