He was born in
Francavilla Fontana in
Apulia, in the
Kingdom of Naples, into an aristocratic family which had come from
Genoa. In 1662, he was sent to
Rome with three brothers to live with his great uncle, Cardinal
Lorenzo Imperiali (1612 - 1673). Lorenzo was a son of the Genoese nobleman Michele Imperiali. In Rome, Giuseppe studied at the
Collegio Germanico-Ungarico, and in 1672 he was made
referendary of the
Segnatura. In 1688, he entered a religious order. In 1684 he gained the lucrative post of
Chierico della Camera Apostolica in the papal finance office; in 1688, he rose to become Treasurer General of the Holy Roman Church. In the Consistory of 13 February 1690 he was made a Cardinal by
Pope Alexander VIII, and was assigned the Deaconry of
San Giorgio in Velabro on 10 April 1690. He was soon sent to
Ferrara as papal legate and remained there for seven years. Back in Rome, during the
Conclave of 1700 Imperiali was part of a group of cardinals who were trying to resist the pressure applied by foreign governments aiming to influence Papal elections, and they obtained the election of cardinal Giovanni Francesco Albani as
Pope Clement XI. Clement in turn, rewarded Imperiali in 1701 by appointing him to the powerful position of Prefect of the
Congregation of Buon Governo. In this position, he controlled funding for public works projects in the
Papal States. Among these he commissioned the aqueduct of Benevento and the new façade of the Cathedral of
Poggio Mirteto from
Carlo Buratti. Among his other endeavours was his attempt in 1720 to influence the Republic of Genoa to arrest Cardinal
Giulio Alberoni. Upon the death of Benedict XIII in 1730, Cardinal Imperiali was touted as a candidate for the Papacy. In the
Conclave of 1730, however, the opposition of the cardinals of the French and Spanish interest ensured that Imperiali failed to obtain the two-thirds required to be elected as pope, and instead Lorenzo Corsini was chosen and took the name
Pope Clement XII. Imperiali continued to serve the Vatican in prominent roles until he died in Rome in 1737, at the age of 85. He was buried in the church of
Sant'Agostino. His nephew,
Cosimo Imperiali (1685–1764), also became a cardinal. ==Formation of the Imperiali Library==