Not much is known about the early career of Cotta, who was born into the Plebeian gens Aurelia.
During his tenure in office, he, along with his colleague Lucius Caecilius Metellus Dalmaticus, opposed the passage of a law proposed by Gaius Marius, then a Plebeian tribune, which was meant to reform the configuration of the voting booths, thereby reducing the influence of the so-called Optimates.
[2] After Cotta's colleague Metellus was imprisoned on Marius’ orders, Cotta and the Senate backed down and allowed the passage of Marius’ law.
During his year in office, Cotta may have fought alongside Metellus in the campaign against the Dalmatians; the remaining sources are unclear if he actually participated or not.
He had at least two children: one son with the same name who then become the consul in 65 BC and one daughter, Aurelia Cotta, who later was married to Gaius Julius Caesar and bore him three children, two of which were the dictator Julius Caesar and Julia Minor, the first Roman emperor Augustus's maternal grandmother.