Throughout the 1630s, Donghi was employed in a number of administrative positions in
Rome including
referendary of the
Tribunals of the Apostolic Signature of Justice and of Grace. On 15 June 1635 he was appointed Protonotary Apostolic
de numero participantium and Cleric of the Apostolic Camera (Treasury). He rose to the post of President of the
Apostolic Chamber. In 1643 he acted as
commissary-resident for the three
legations held by Cardinal
Antonio Barberini over regions in which he did not reside - effectively operating as the cardinal's representative in those regions when the cardinal was not there. He was also sent by the pope as legate to
Lombardy during the
First War of Castro to reach a peace agreement with the
Dukes of Parma after the pope renounced the peace agreement negotiated by Cardinal
Bernardino Spada. He was then named Protonotary Apostolic at the Datary. Urban died a year later, on 29 July 1644, and Donghi was one of the fifty-seven cardinals who participated in the
papal conclave of 1644. The Conclave opened on 9 August, and resulted in the election of
Pope Innocent X on 15 September 1644. Donghi was openly a part of the
Spanish faction of the
College of Cardinals. An inscription in Ravenna, dated 1654, commemorates Donghi's providing supplies of grain to the city during a famine. He was elected Bishop of Ajaccio, Corsica, on 27 November 1651. Pope Innocent X died on 7 January 1655. The Conclave to elect his successor opened on 18 January. Donghi was one of sixty-six cardinals who participated in the
Conclave of 1655. On 7 April, after much twisting and turning over the candidacies of Cardinals Sacchetti, Carafa and Chigi, the Cardinals elected Fabio Chigi, who chose the throne name
Pope Alexander VII. On 14 May 1655 Cardinal Donghi was transferred from the Deaconry of San Giorgio in Velabro to the Deaconry of
S. Agata. On 2 August 1655 Donghi was appointed
bishop of Imola. In Imola he conducted a pastoral visitation throughout his diocese, and then, in 1659, held a diocesan synod. He also received Queen Christina of Sweden as she was on her way to Rome. On 26 February 1663, Cardinal Donghi was released from his commitment to Imola, and appointed
bishop of Ferrara; he held the diocese until his death. Pope Alexander died on 22 May 1667. The Conclave to elect his successor began on 2 June. Ultimately sixty-four of the sixty-eight cardinals participated, including Giovanni Stefano Donghi. The likely candidates seemed to be Cardinal Girolamo Farnese (the French supported him, and the Cardinal nephew Chigi was favorable), Scipione d'Elci (the preference of the Grand Duke of Tuscany, to whom Chigi was also favorable), and Giulio Rospigliosi. On 20 June the
Conclave elected Giulio Rospigliosi, who became
Pope Clement IX. On 12 March 1668, Cardinal Rinaldo d'Este accepted promotion to the rank of Cardinal Priest of S. Pudenziana, which automatically made Cardinal Donghi the senior Cardinal-Deacon in the Sacred College (Protodeacon). Cardinal Giovanni Stefano Donghi died on 26 November 1669 and was buried in the
Chapel of the Madonna at the
Church of the Gesù in Rome. There is no monument or inscription. ==References==