PSG seal deal for Milan defender Silva
The 27-year-old, regarded as one of the best defenders in the world, joined Milan from Fluminense in 2008.
"The Brazilian international Thiago Silva is joining Paris Saint-Germain for five years," PSG said in a statement on their website.
The club did not give any financial details of the deal but local media estimated the transfer fee at 40 to 45 million euros.
Thiago Silva is PSG's second signing of the close season after the club from the French capital signed Argentina forward Ezequiel Lavezzi from Napoli earlier this month.
Qatar-backed PSG have also been widely reported by local media to be in talks with Zlatan Ibrahimovic's agent to buy the Sweden forward from Milan.
Last season, they strengthened their squad by signing Argentina playmaker Javier Pastore, Brazil defender Alex and Italy's Brazilian-born central midfielder Thiago Motta.