Son of Senator Annibale Brandolini, he was the member of the Brandolini family of Venetian descent and possessed the titles of Count of Valmareno, Lord of Solighetto and Venetian patrician.
With the Royal Decree of 26 November 1914 he was able to add the surname of his mother, Leopolda D'Adda, to his own.
He became senator on 16 October 1913 with Antonino Di Prampero as rapporteur.
On 20 February 1898[1] in the chapel of Ca' Vendramin Calergi, Girolamo Brandolini married Gabrielle Lucchesi-Palli (1875–1937), the daughter of Hector Adinolfo Lucchesi-Palli, 9th Duke della Grazia, Prince of Campofranco (10 March 1840 – Brunsee,[2] Styria, Austria, 4 February 1911), son of Marie-Caroline of Bourbon-Two Sicilies, Duchess of Berry, and his wife, Lucrezia Nicoletta, née Sasso-Ruffo dei principi di Sant' Antimo.
[4] On 10 June 1925, his son Annibale Brandolini d'Adda married Laura Boncompagni Ludovisi of the House of Boncompagni, the daughter of Francesco Boncompagni Ludovisi, prince of Piombino and of princess Nicoletta, née Prinetti Castelletti.