And the former World Player of the Year seemed happy to have finally closed the door on his time in Spain and looked forward to returning to his best in the Serie A.
"This is a special moment in my career. I already feel at home," he said. "Everyone dreams of playing for Milan, because of how important his club is. Pulling on this shirt is already a victory.
"My time at Barcelona was a good period, I won so much. In the last few years, however, we didn't manage to win a trophy. It became a bit of a disappointment and we decided to part ways.
"I'm very happy to be here. I want to come here to win."
Despite previous concerns over the fitness of the Brazil star, Milan vice-president Adriano Galliani, who sat alongside Ronaldinho throughout the press conference, told the gathered reporters he had come through the medical "brilliantly".
"A dream has been achieved after so many years. I'm very happy," Galliani said. "We have never followed a player for so long. Finally after three years of closely following the player we have done it.
"We've brought a great champion to the club. He will put the final signature on his contract later, but we can finally announce that he is a Milan player."
Before being led out onto the San Siro pitch to be presented to the fans, Ronaldinho revealed he was keen to link up with his Brazil team-mates Dida, Emerson, Alexandre Pato and especially Ballon d'Or winner Kaka.
Questions had been raised over the compatibility of the duo, but Ronaldinho was sure he could former an effective partnership with his compatriot.
"Kaka is one of the best players in the world and a friend," he said.
"I don't see any problems playing with him, it'll be good. I've played with him before and I'm sure it will work.
He added: "My team-mates from the national team always told me about Milan, they always told me great things and that fuelled my curiosity."
Ronaldinho conducted the press conference in a Milan shirt without any squad number on the back.
The Brazilian has famously worn the number 10 shirt during his career, but the occupant of that shirt at Milan, Clarence Seedorf, has already revealed he will not change numbers.
When asked which number he would wear instead, Ronaldinho added: "It's not been decided yet."