The 33-year-old, widely considered one of the greatest footballers of all time, has put pen to paper on a four-year deal in Turin, ending his illustrious nine-year stay at Real Madrid.
Berlusconi, who sold Milan to Yonghong Li last year, believes that the move is a coup for Italian football, even if the Rossonero in him is upset.
"What effect has seeing Ronaldo going to Juve had on me? As a Milanista, a terrible effect!" Berlusconi told Il Giornale.
"But in truth, the arrival of an absolute champion like Cristiano Ronaldo in the Italian league is good news.
"That isn't just for Juventus, but for all of Italian football. So I congratulate Juve, their directors and fans."
Ronaldo, a five-time Ballon d'Or winner, will be unveiled by his new club on Monday.