The Younger Balbus, referred to in Cicero's letters as Balbus minor, followed the example of his elder by entering politics, first in support of Caesar and then Octavian. He was sent on difficult diplomatic missions by Caesar in 49 (about which he wrote a lost fabula praetexta) and 48 BCE.

Velleius Paterculus writes of Balbus, on his mission to the war camp of Pompey at Dyrrachium in 48 BCE, that he showed a "rashness beyond human confidence": Tum Balbus Cornelius excedente humanam fidem temeritate ingressus castra hostium saepiusque cum Lentulo conlocutus consule. Paterculus saw that Balbus' extraordinary political advancement was brought about by his daring service to the Julian family in both civil wars: "by such steps he made his way, born not in Spain of a citizen, but himself a Spaniard; he rose to a triumph and a pontificate and was made consular in rank from a private citizen," illis incrementis fecit viam, quibus non in Hispania ex cive natus, sed Hispanus, in triumphum et pontificatum adsurgeret fieretque ex privato consularis.( Historiae Romanae 2.51).

Balbus was appointed proquaestor in Further Spain in 43 BCE under Pollio. As proconsul of Africa in 21/20 BCE, he distinguished himself by defeating the Garamantes and extending Roman control over other warring tribes along the borders of his province. As a result he was awarded a triumph by Augustus on 27 March 19 BCE, a pontificate and consular rank . His triumph, a unique distinction for a foreign-born Roman, was the last permitted to a provincial governor who was not a member of the imperial family.

Suetonius writes (Vita Divi Augusti 29.4-5) that Balbus, among other principes viros, was encouraged by Augustus, through word and model, to adorn the city with new monuments or restore older ones, according to their means. Balbus' response was the construction of the splendid theater and portico in the Campus Martius, which he named after himself. To this Tacitus adds: " Public-spirited munificence was still in fashion, and Augustus had not hindered Taurus, Philippus, or Balbus from applying the spoils of war or their superfluous wealth to adorn the capital and to win the admiration of posterity " Annales 3.72.

Balbus Minor was, like Maior, a patron and benefactor of his home town, Gades, where he sponsored new buildings and docks.