Zuculini has been with the club during the pre-season tours of Scotland and the USA where he is understood to have made a favourable impression on manager Manuel Pellegrini.
The 21-year-old scored in City’s 4-1 friendly win against MLS side Sporting Kansas City and joins the club from Buenos Aires-based Racing Club, where he has made 92 appearances, scoring 10 goals.
It is thought the youngster - whose elder brother Franco is a full Argentina international - is seen as one for the future by City boss Pellegrini.
Zuculini has been handed the number 36 shirt by the club and is available for selection at Sunday's Community Shield clash against Arsenal at Wembley.
Speaking to City’s official website, Zuculini said: "I'm very excited about the future. I am looking forward to the experiences which this move will bring and to improving myself as a player."