Marini was baptised in the patriarchal Vatican basilica in 1794; his godfather was Cardinal Gregorio Barnaba Chiaramonti, O.S.B.Cas., the future Pope Pius VII.

Marini studied letters and philosophy at the Pontifical Roman Seminary from 1804 to 1810; then, at La Sapienza University, Rome, obtaining a doctorate ad honorem in utroque iure (both canon and civil law) on 24 July 1816.

Marini served as a civil assessor of the province of the Romagna from 1817 to 1820; before being named patrician of Ravenna by the city in 1820.

He was appointed governor of Rome, vice-camerlengo of the Holy Roman Church and director general of police on 22 April 1845, serving until 21 December 1846.

After lying in state in the church of San Carlo ai Catinari, the funeral took place on 24 August 1863, with Pope Pius IX participating.