The 21-year-old has joined the League Two side on a three-month loan deal.
“It’s a done deal,” Rotherham manager Ronnie Moore told the club’s official website.
“It is fantastic for the club that Arsenal have allowed a player to come out who has played 13 first team games.
“He will train on Monday and be in contention to play for us in the game at Southend next weekend.”
