Arsenal have announced the signing of Lucas Torreira from Sampdoria for an undisclosed fee.
"We have signed a young player who is a very bright talent in the game, a midfielder with great quality," Emery told the club's official website.
Torreira was one of Uruguay's key players in their progress to the quarter-finals of the 2018 FIFA World Cup.
He has been given the No 11 shirt and will join Arsenal for pre-season in early August.
Arsenal's 2018/19 Premier League begins at home to champions Manchester City on 12 August.