His career included his election as pontifex in 73 BCE, quaestor in 69, and pontifex maximus in 63. Upon the death of Cornelia in 69 he married second Pompeia. He divorced Pompeia in 62 over he involvement in a fertility scandal. He became a praetor in 62 and went on to become the governor of Spain in 60.  Elected consul in 59 he joined with Pompey and Marcus Licinius Crassus to establish an informal alliance known as the First Triumvirate. That same year he married third Calpurnia the daughter of consul Lucius Piso. He conducted campaigns in the Gallic Wars, 58-50, extending Roman power.

Declared emperor for life in 44, he became a threat to a group of Roman senators who believed he had become too powerful. These angry politicians, led by Brutus and Cassius, feared he would become an absolute king bent on further restricting the Senate and undermining the republic. They plotted his assassination and successfully carried out their conspiracy on March 15 (the Ides), 44 BCE, when they murdered him.