The 6-foot-8, 250-pound Carter averaged 11.4 points and 8.4 rebounds per game last season. He will sit out this season and have two years left for the Terps.
Carter is a huge boost for Maryland coach Mark Turgeon, who has had numerous players transfer out of the program this past offseason, including guards Seth Allen and Nick Faust.
"We're excited to welcome Robert to the University of Maryland men's basketball program," Turgeon said in a statement. "... He is a complete player with a strong offensive skillset that complements his desire to rebound and defend. Our program is thrilled to have him as we transition into the Big Ten."
Maryland finished 17-15 last season and 9-9 in the ACC.