Caesonius Lucillus occupied a succession of posts: the junior magistracy of the decemvir stlitibus judicandis; a quaestor; and a praetor, all sponsored by the emperor, Caracalla (r. 211–217).

This career path from quaestor to praetor as an imperial candidate was standard during the third century for ascent up the cursus honorum, the traditional series of military, administrative and judicial positions of steadily increasing responsibility which aspiring upper-class Romans were expected to progress through.

[4] After serving as consul, in c. 227–230, Caesonius Lucillus was given the responsibility for maintaining the channels of the Tiber River (Curator alvei Tiberis et cloacarum urbis) as well as the sewers of ancient Rome.

In 238 he was chosen as one of the group of twenty senators who temporarily took over the government of the empire after the rebellion against Maximinus Thrax and the unexpected death of Gordian I (vigintiviri ex senatus consulto rei publicae curandae).

This was followed by his appointment as the official deputising for the emperor in overseeing judicial cases (Electus ad cognoscendas vice Caesaris cognitionis); this was probably between 242 and 244 when Gordian III was conducting his Persian campaign, but it is possible that he may have held this post at any time before 254.

Caesonius Lucillus’ final posting was as praefectus urbi of Rome, the senior administrative position of the capital with responsibilities similar to those of an executive mayor.