The attacker looks set to quit Real Madrid this summer, as he nears a shock €100m (£88m) move to the Serie A giants.
Ronaldo has threatened to leave the Spanish capital over the years, usually in the hope of receiving a new bumper deal from the club.
But this time it appears the 33-year-old really is heading for the exit door.
And Alves, who has played alongside Ronaldo for Portugal for over a decade, believes his team-mate will be a success at Juventus.
“Cristiano Ronaldo will only win again at Juventus,” he told Portuguese outlet O’Jogo.
“There is no championship where he can not be successful, he has already demonstrated on several occasions that he can win in any country and in Italy it will not be different.
“I support him, he is a testimonial of Portugal in the world.
“I have been at his side in many battles for twelve years and I know how he is able to motivate himself and for this reason it is important to accept a new challenge.”
Ronaldo has also been linked with a move to Manchester United this summer.
However, the Premier League outfit have not yet launched a bid for their former star.
Ronaldo has, however, rejected a £176m contract offer from an unnamed Chinese club, according to Marca.