Stansbury, 54, was fired a year ago after 14 seasons in Starkville. He was 293-165 in his tenure and went to the NCAA tournament six times.
"I am happy that Rick decided to join my staff," Kennedy said in a statement. "His experience in the SEC and his recruiting ties are going to help immediately. He has won championships in this league and will help us on and off the court. I'm excited that Rick and his family are coming to Aggieland."
Texas A&M finished 18-16 last season, Kennedy's third in College Station.
"I'm excited to be a part of coach Kennedy's staff," Stansbury said in a statement. "I've known Billy for a long time, he's a terrific coach and even better person. I look forward to helping him and his staff in any way I can."