Cardinal Sardi was born on September 1, 1934 in Ricaldone, Italy.
He was ordained a Priest on June 29, 1958 for Acqui, Italy, and on December 10, 1996 he was appointed Titular Archbishop of Sutrium and Official of the Secretariat of State. His ordination as Bishop took place on January 6, 1997.
On October 23, 2004 he was appointed Vice-Chamberlain of the Apostolic Chamber, a position that he retired from upon his appointment as Caridnal.
On November 20, 2010 he was appointed Cardinal-Deacon of Santa Maria Auxiliatrice in via Tuscolana and elevated to Cardinal. He was installed on May 24, 2011.