The 24-year-old, who joined the club two years ago, has signed a deal which will take him up until June 30, 2010.
“Juventus have reached agreement with Inter Milan for the signing of Zlatan Ibrahimovic for 24.8 million euros payable over three years,” the buying club said in a statement.
Juventus had claimed after the sale of France captain Patrick Vieira to Inter Milan last week that no more players would be allowed to leave.
But Ibrahimovic demanded out in the wake of Juve’s demotion to Serie B – along with a 17-point penalty for the coming season – for their part in Italy’s match-fixing scandal.
Juventus were also stripped of the league titles they won last season (2005/06) and the season before and barred from the Champions League.
He becomes Inter Milan’s fourth signing for the new season after Vieira, Fabio Grosso (Palermo) and Hernan Crespo (Chelsea).
Ibrahimovic joined Juventus from Dutch side Ajax in 2004, scoring 26 goals in the past two years.