Scaurus lost his father when he was very young, but his education was ensured by family friends. Pompey the Great was briefly married to his sister Aemilia and, even after her death, Pompey continued to take personal interest in the young man.
During the Third Mithridatic War, Pompey specifically asked for Scaurus to become his military tribune, and charged Scaurus, at the time a quaestor, with the responsibility for the Judea region, which was involved in a bloody civil war between the brothers Hyrcanus and Aristobulus. Caught in a siege by the Nabatean king Aretas III, Aristobulus asked for Pompey's intervention through Scaurus, and offered an enormous bribe. After Scaurus convinced Aretas to end the siege (64 BC), Aristobulus accused Scaurus of the extortion of 1000 talents, but Pompey, who trusted his brother-in-law, decided to give Judea to his opponent Hyrcanus (63 BC).
In 62 BC, when Pompey returned to Rome, Scaurus moved to Petra, capital of the Nabatean Kingdom, where he relieved the siege after receiving a bribe of 300 talents. In 58 BC, as aedile, Scaurus organized the Aedilician Games, long remembered for their extravagance.
Praetor (56 BC) and propraetor (55 BC) in Sardinia, Scaurus was supported by the First Triumvirate for the consulship in 54 BC, but was accused of extortion in his province. Scaurus was defended by Cicero, and acquitted in spite of his obvious guilt. In 53 BC, however, he was accused of ambitio (shameless bribery) and went into exile.
Scaurus' massacres are mentioned in the Dead Sea scrolls (4Q333). He was said by Pliny the Elder to have been the first Roman collector, or major collector, of engraved gems (Natural History, Book 37, Chapter 5).