Marshall, a football and track star from Millbrook High in Raleigh, N.C., said at a news conference at his school on Tuesday he chose Georgia over Clemson.
Rivals.com, Scout.com and The Sporting News rank Marshall as their No. 1 running back prospect.
This is the second straight year Georgia has landed one of the nation's top running backs. Isaiah Crowell, from Carver High in Columbus, led No. 18 Georgia in rushing this season and on Monday was named the Southeastern Conference's Freshman of the Year by The Associated Press.
Marshall says he will enroll at the University of Georgia in January.