The 34-year-old, who also played for Paris St Germain and AC Milan, became a free agent in July after cancelling his contract with Brazilian club Atletico Mineiro.
"We are very pleased to add to our ranks as of today, a player who has excelled in international football. A world champion in 2002, World Player of the Year in 2004 and 2005," the club, nicknamed 'Gallos' said in the statement.
"We hope the fans of our city and around the country join in this celebration of having Ronaldinho as a Gallos who will contribute his experience and expertise to further strengthen this great team,” the club added.
Queretaro are currently eighth in Liga MX after seven matches in the championship.

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