Around 91 BC Livianus succeeded his brother Marcus Livius Drusus as one of the pontifices in the College of Pontiffs.
He achieved some victories, most notably he was credited with killing the general of the Marsi, Quintus Poppaedius Silo, during the storming of Venusia.
[6] He ran for the office of consul in 77, achieving it only after Gaius Scribonius Curio withdrew his candidature for that year in favor of Livianus.
[7] Neither Mamercus nor his consular colleague accepted a proconsular command in Hispania to help Quintus Caecilius Metellus Pius in the Sertorian War.
[9] Following his term as consul Livianus was probably a promagistrate serving under Marcus Antonius Creticus in 74, who had been given an extraordinary commission to clear the Mediterranean Sea of pirates operating from Crete.