His date of birth is not known, but he was an adult during the late 60s BC, at which time he was described by Julius Caesar as a "senator" of the Aedui. In Caesar's The Gallic War the word "senator" is used to refer to Gallic aristocrats who took part in their clans' decision-making. He supported the Aedui's preexisting alliance with Rome.
In 63 BC, at the age of 32, he survived the Battle of Magetobriga, where forces of the Sequani and Arverni, together with Germanic troops under the Suebi King Ariovistus, massacred the Aedui. Thereafter, the Aedui became tributary to the Sequani. Following the Aedui's defeat at Magetobriga, Diviciacus traveled to Rome and spoke before the Roman Senate to ask for military aid. While in Rome, he was a guest of Cicero, who spoke of his knowledge of divination, astronomy and natural philosophy, and names him as a druid. Julius Caesar, who knew him well, noted his particular skills as a diplomat without calling him a druid.
Following Caesar's victory over the Helvetii, Diviciacus went as a prominent member of the Gallic delegation to Caesar, and was appointed as their chief spokesman. He brought the Gallic people's concerns to Caesar over Ariovistus, who had taken much of the Sequani lands and taken hostages. The Gaul's request provided the catalyst for the next phase of Caesar's Conquest of Gaul, when Caesar went on to confront and defeat Ariovistus.
Diviciacus had a brother, Dumnorix, who was aggressively anti-Roman. After defeating him in battle, Caesar spared his life so as to avoid antagonizing Diviciacus. Later, however, Dumnorix attempted to escape from Caesar's control and was killed in the attempt.
Delamarre contends that, in addition to holding the religious office of druid, Diviciacus may have been the Uergobretos, the annually elected political leader or chief magistrate of the Aedui, one of the most powerful nations in Gaul. If true, his combination of military and religious office responsibilities in Aedua paralleled Caesar's duties among the Romans. For in Rome, Caesar was Pontifex Maximus in addition to being a magistrate and general. Diviciacus would have been Uergobretos sometime before 52 BC, when the election was contested between Convictolitavis and Cotos. The date of Diviciacus's death is not known; Cicero speaks of him in the past tense in 44 BC.
Diviciacus appears as a special Druid unit in the video game Praetorians, part of which is set during the Gallic Wars. In the game, Diviciacus serves as a healer frequently appearing on the side of Rome during the campaign. His name is spelled 'Divitiacus'.