A number of elite European clubs, including French giants Paris Saint-Germain and Manchester United, were understood to be tracking the Brazilian attacking midfielder before Milan struck a deal to secure his signature.
The Rossoneri are reported to be paying €35 million (£31m/$40m) for the star.
The 21-year-old scored 10 goals and provided four assists in 39 games in all competitions in the Brazilian season, which has now ended.
And with the campaign now over, Paqueta has travelled to Italy to formalise his move to the San Siro giants.
Paqueta has been dubbed the 'new Kaka' and will follow in his legendary compatriot's footsteps by making Milan his first step in European football.
“Lucas thinks about football in the same way as Neymar and [Philippe] Coutinho,” the Selecao coach enthused when asked about the Rio native.
“When we played against El Salvador he had a series of exchanges with Neymar, practically without having seen him before and without playing together. They linked up with their eyes closed.”
Kaka, meanwhile, is already a fan of Paqueta, though he does not believe comparisons between himself and the youngster are helpful.
"He's already been called up to the Brazilian national team, but it's better for him that we don't make comparisons. I've seen so many of them in recent days, with me, with [Alexandre] Pato, with Ronaldinho, Cafu, Rivaldo… with all the Brazilians who have been part of Milan's history.
"We need to avoid these comparisons so he can come here and play calmly and peacefully. But I'm confident."
The midfielder will be registered as a European player, per Calciomercato, due to his mother's Portuguese heritage.
That will leave Milan with two non-EU squad slots that they can fill in the January transfer window.