The 6-foot-6, 235-pound Clark played one season at Charlotte, starting 18 games and averaging 6.2 points and 4.6 rebounds in 17.6 minutes per game. He made 54.2 percent of his field goal attempts.
"Darion fits our style of play. We are excited to have him," USC coach Andy Enfield said. "He will sit out this season, develop his skills and have three years remaining to help take the USC program to the next level."
Clark is from Conyers, Ga., and attended Oak Hill Academy, where he helped lead the school to a 44-0 record and ESPN's final No. 1 ranking in 2012.