The Brazilian left Milan earlier this summer.
"When President Silvio Berlusconi blocked everything, I was a little surprised, but also relaxed as I was working with the Brazilian team at the Olympics," revealed Thiago Silva in his presentation.
"It was not easy to leave Milan, for me or for the club, but it was my choice and I stand by it. I had nothing to complain about during my three years at Milan and was treated well from the start.
"I gave everything I had. I wish the Rossoneri fans well and left them with great sadness. Now I am happy to be here and hope to do as well with Paris Saint-Germain as I did at Milan. I have belief in this project and want to be a part of it."