Italian organist and musicologist, graduated in piano and organ with the highest honors from the «L. Cherubini» Conservatory of Firenze, where he studied with Mariella Mochi. He then completed special studies with Stefano Innocenti and took courses in musical interpretation with Luigi Ferdinando Tagliavini, Michael Radulescu and Harald Vogel. He earned his baccalaureate degree in the history of music with highest honors at the University of Florence.

He gave concert performances in Europe (Austria, Belgium, Denmark, France, Germany, Great Britain, ex-Jugoslavia, Netherland, Russia, Slovakia, Slovenia, Spain, Sweden …) and America (Peru, Uruguay, USA), invited by associations and istitutions as: Sagra Musicale Umbra, Festival «Organalia» in Turin, Festival «G. Callido» di Venezia, Organ Festival Oudekerk in Amsterdam, Tretjakovskaja Galereja in Moscow, St. Johannes Orgelfestival in Copenhagen, Organ Festival in Saint Jacobskyrkan in Stockholm, Concerts in Stockholm Storkyrkan, Festival M. Leclerc in Sens's Cathedral, Festival d'Orgue en Flandres, Organ Concerts in Winchester Cathedral, Organ Concerts in Ljubljana Cathedral, Festival Internacional de Organo de la Catedral de Getafe (Madrid), St.Johanniskirke Organ Festival in Altona-Hamburg, Festival Iberomericano de mùsicacolonial, Festival Internacional de Organo del Uruguay, Festival Barroco de Cuzco, OrganConcerts in Central Synagogue of New York, etc. He recorded a CD (Elegia Records) entitled Domenico Zipoli from the Old World to the New on the ancient organs of his city (4 stars and "grande fantasia e sensibilità" on «Musica») in which he played the historical organ of the Prato'sCathedral, and a CD (Tactus) entitled Organ Music in Florence from the Medici to Italy'sUnification (5 stars on «Amadeus», 4 stars on the british review «Choir&Organ», "excellent interpreter" in «Musicweb International», "allgreatfun!" in «Early Music Review») in which he played the historical organs of the San Lorenzo church in Florence. Giacomelli is member of the artistic commission of the Accademia di Musica Italiana per Organo di Pistoia and juror in the International Organ Competition Agati-Tronci.

His articles have been published in scholarly journals (Informazione organistica, L'Organo, The Organ Yearbook, Recercare, Il Saggiatore Musicale ...) and in books published by Libreria Editrice Vaticana, LIM, Marsilio, Olschki, Yale University Press ... He has written entries for the dictionary Musik in Geschichte und Gegenwart (Bärenreiter) and for the Dizionario Biografico degli Italiani (Treccani). He has authored three books: Antonio Squarcialupi e la tradizione organaria in Toscana, (1992); Gli organi di S. Maria del Fiore di Firenze (1993); O flos colende. Musica per Santa Maria del Fiore (1998). He is coauthor with the violinist Salvatore Accardo of the text books Stradivari (Bompiani 2012) and Sulle note di uno Stradivari (Fabbri 2017). Giacomelli is Supervisor of the Italian Culture's Ministry for the restoration of the ancient organs of Florence. He transcribed and published some music of authors like Marco da Gagliano and Domenico Zipoli.

He is artistic director of the musical series: O flos colende. Musica sacra a Firenze, organized by the Florence's Cathedral since 1997, and of the Festival Zipoli promoted by the Commune of Prato since 1998. Since 2016 he is artistic curator of Passeggiate Musicali - Antichi Suoni of the Festival del Maggio Musicale Fiorentino. He taught as invited professor at the University of Firenze and Lecce. He did lectures in many countries (Europe and America) focusing organ and sacred music in Italy from Renaissance to Baroque period. He is professor of History of Music at the «G. B. Martini» Conservatory in Bologna.