The highly rated 19-year-old Brazilian defender has made the switch from Roma to the Ligue 1 champion, in a deal reportedly worth 35 million euros.
The 19-year-old, who has signed a five-year deal, was only with the Giallorossi for one season, having joined from Brazilian side Corinthians in July 2012.
"I am delighted to be joining Paris Saint-Germain, a club where so many Brazilians have played and helped write the club's history," Marquinhos told the club's official website. "I will do everything I can to continue that tradition and write my own name into the club's illustrious history books.
"Paris Saint-Germain will help me continue my progression alongside exceptional players, with the desire to win trophies and also win the hearts of the supporters."
Marquinhos had been linked with a host of top European clubs, including Manchester United and Barcelona, following an impressive debut season in Serie A.
"The arrival of Marquinhos, whose qualities have attracted the interest of major European clubs, is a real satisfaction for Paris Saint-Germain," PSG president Nasser Al-Khelaïfi added.
"It marks our commitment to project ourselves into the future to build one of the biggest teams in Europe."
PSG has already signed left back Lucas Digne from Lille and Edinson Cavani from Napoli as it looks to strengthen its bid for Champions League glory next season.