In 1814 the Riccardi sold their palazzo in Via Larga to the Lorraine, the rulers of the Grand-duchy of Tuscany. Meanwhile, the previous year, the Municipal Council of the City of Florence had purchased the Biblioteca Riccardiana, which it then handed over to the State.
The premises of Palazzo Medici Riccardi, now State property, were given over to be used as administrative offices for various bodies, and significant rebuilding work was performed.
After the Unification of Italy, between 1865 and 1870 while Florence was the capital of the nation, the palazzo became the headquarters of the Home Office.

In 1874 the building was purchased by the Florence Provincial Authority, which is still the owner. The Authority then set up its own offices in the new premises, including the apartment of the Prefect, or Provincial Governor, which is still here, and other institutions. It also transferred the Biblioteca Moreniana to a series of rooms adjacent to the Biblioteca Riccardiana. To adapt the palazzo to its new role, a further campaign of modifications was undertaken.