He attended the liceo scientifico of Scandicci before entering the Archiepiscopal Major Seminary of Florence [it] in 1978.

[1] In 2002, Manetti became the spiritual director of the Archiepiscopal Major Seminary of Florence and was appointed a canon of the chapter of the Basilica of San Lorenzo.

The principal consecrator was Cardinal Giuseppe Betori, the Archbishop of Florence, and the principal co-consecrators were Cardinal Piovanelli, the Archbishop Emeritus of Florence; Cardinal Gualtiero Bassetti, the Bishop of Perugia–Città della Pieve; Claudio Maniago, the Auxiliary Bishop of Florence; and Rodolfo Cetoloni, the Bishop of Grosseto.

[4] As a member of the Tuscan Episcopal Conference [it], he was a delegate for clergy, seminaries, and vocations.

[1] On 21 April 2022, Pope Francis appointed Manetti to succeed Mario Meini as the Bishop of Fiesole.

[6] Manetti remained as apostolic administrator until 3 September 2022, when Augusto Paolo Lojudice took possession as the archbishop-bishop[a] of the diocese.