Guido Marini (born 31 January 1965) is an Italian prelate of the Catholic Church who serves as the bishop of Tortona in northern Italy.

Before joining the papal household, Marini worked in the Archdiocese of Genoa, where he was the personal secretary to three archbishops from 1988 to 2003, chief liturgist from 2004 to 2007, and chancellor from 2005 to 2007.

He then earned a degree in both canon and civil law (JUD) from the Pontifical Lateran University with a dissertation on problems of church-state relations in the early 20th century.

Marini said that from now on – starting from 29 June 2015 – the ceremony of investiture of the pallium will take place in each metropolitan archbishop's home diocese and not in the Vatican.

[citation needed] In 2019, Pope Francis made Marini's office responsible for the Sistine Chapel Choir, which until then operated independently within the papal household.