Pompeianus, a Syrian of lowly birth, served as a general in the Germanic wars under Marcus Aurelius. During this time he gave much support to the young Pertinax, who was later to become emperor for a brief time after Pompeianus himself refused to take the throne.
After Lucian's death in 169, Pompeianus married his widow Lucilla, Marcus Aurelius' daughter. It seems Aurelius had been contemplating appointing Pompeianus to the position of Caesar, a possibility supported by the haste with which Aurelius arranged Pompeianus' marriage to Lucilla. It is quite possible that such an offer had actually been made and declined by Pompoeianus.
Pompeianus served as Imperial Roman Consul in 173.
In 182, Pompeianus' wife, Lucilla was involved in a plot with members of the senate to kill Commodus, who was emperor and her brother. The plot called for Pompeianus' newphew to stab Commodus, and the young assassin, during the attempt, declared to Commodus "Here is the dagger the senate sends to you", giving away his intentions before he had the chance to act. Commodus foiled the attempt in progress and had the conspirators, including many important senators, executed. Lucilla was exiled to Capri and there was soon executed. Pompeianus, who had not himself been involved in the plot, retired temporarily from public life.
He spent most of his time in the country away from Rome, claiming age and an ailment of the eyes as an excuse.
After the death of Commodus in 193, Pertinax offered the throne to Pompeianus, but the offer was declined. Pertinax himself took the throne and was stabbed to death in a praetorian rebellion after a reign of only 87 days.
Pompeianus, however, did return to public life once the plot against Commodus had succeeded, no longer complaining of poor health or eye ailments. He took part in the deliberations of the senate and sat bench beside Pertinax.
Didius Julianus, after becoming emperor by winning an auction the Praetorian Guard held for the title, experienced difficulty in garnering support even within the ranks of his own troops and, in a desperate attempt to save himself, asked Pompeianus to be co-regent with him, but this offer too was declined. It seems that once again Pompeianus complained of old age and ailments of the eyes. Julianus was executed by a common soldier on the orders of Septimius Severus on June 1, 193 after ruling for only 66 days.