[2] In October 1679 in Rome he took the offices of Prefect of the Annona with the responsibility for the grain supply to the city of Rome, and in 1681 he became General Treasurer of the Apostolic Camera, working with Pope Innocent XI to reduce the expenses of the Papal States, and in that position he succeeded to perform a restructuring of the debt of the State.

[2] On 2 September 1686, Pope Innocent XI appointed him Cardinal deacon with the title of San Cesareo de Appia.

[2] During the 1691 papal conclave, Negroni wrote a manifesto for the faction of the zelanti cardinals, who desired that the election of the Pope were free from nepotism and from the interferences of France, Spain and Holy Empire.

[6] In the same conclave, with compromising documents he stopped the candidature of Paluzzo Paluzzi Altieri degli Albertoni, the Cardinal-Nephew to Pope Clement X.

[4] He resigned the bishopric of Faenza on 11 November 1697, passing the last years in Rome, where he died on 1 January 1713.