Lucius was son of Marcus Antonius, the son of the great rhetorician Marcus Antonius Orator executed by Gaius Marius' supporters in 86 BC, and Julia Caesaris a cousin of Julius Caesar. Together with his older brothers Marcus and Gaius, he spent his early years roaming through Rome in bad companies. Plutarch refers the untamed life of the youths and theirs friends, frequenting gambling houses and drinking too much.
Lucius was always a big supporter of Marcus Antonius. In 44 BC, the year of Antonius' consulship and Julius Caesar's assassination, Lucius was a tribune of the plebs. In 41 BC, was consul with Publius Servilius Vatia as his senior partner. In this year, he assisted Marcus Antonius' wife, Fulvia, in the raising of a eight legion army to fight against Octavianus' unpopular policies. After a successful occupation of Rome, they ended besieged in Perusia in the winter of 41/40 BC, where they were forced to surrender by starvation. Octavianus destroyed the city but spared the rebellion's leaders: Fulvia and Lucius were exiled.