[2] At the age of four, he succeeded his father (who died in November 1568) in the government of the State of Mirandola under the tutelage of his mother and uncles Ippolito (?-1569) and Luigi (1526-1581),[3] as well as with the support of King Charles IX of France, who then elected him Capitain, Gentilhomme de la Chambre, and Knight of the Order of Saint Michael.

[4] His mother Fulvia held the regency of Mirandola until her death in 1590, due to the fits of epilepsy from which Galeotto suffered,[3] who decided on 21 February 1592 to cede the government of the Mirandola fiefs and all his allodial possessions to his brother Federico II;[3] the latter, as a sign of respect and modesty, never wanted to publicly use the title of Lord until his brother's death, leaving him the rights and honour of ruling.

[7] At the end of 1596, brothers Galeotto and Federico obtained a pardon from Emperor Rudolf II for what had happened in the previous 60 years and the official investiture of the fiefs.

The arrival of the imperial letters was announced on 25 March 1597, which was followed by festivities for three evenings, with illuminations, the ringing of bells, artillery shots, donations of alms to the poor and amnesties.

[9] After a long period of epileptic fits and fever, Galeotto died on 16 August 1597 at the age of 33 years, and was buried in the church of San Francesco.