His date of birth is not known, but he was an adult during the 60s BC at which time he was a senator of the Aedui and escaped a massacre by the forces of the Sequani, Arverni and Germanic troops under a leader whose Latinised name was Ariovistus (Brunaux, p.282).
He was in favour of alliance with Rome, and in the year 63 BC he went to Rome and spoke before the Senate to ask for military aid; he was a guest of Cicero, who spoke of his knowledge of divination, astronomy and natural philosophy (De Divinatione I xli). Julius Caesar, who knew him well, speaks of him several times in his Commentarii de Bello Gallico and noted his particular skills as a diplomat.
In addition to holding the religious office of druid, he was the Uergobretos (political head or magistrate - see Delamarre p.315)) of the Aedui, one of the most powerful nations in Gaul. In this combination of military and religious office he was similar to Julius Caesar, who was Pontifex Maximus in addition to being a general.
Diviciacus had a brother, Dumnorix, who was strongly anti-Roman. Dumnorix was executed on the orders of Caesar.
Diviciacus had ceased to be Uergobretos by 52 BC, when the election was contested between Convictolitavis and Cotos (Brunaux, p.283). The date Diviciacus's death is not known, but Cicero speaks of him in the present tense in 44 BC.