His career is documented in an inscription found at Rome, which was erected by negotiatores ole ex Baetica, or oil merchants from Baetica, which was one of the most important sources of quality oil; this group had chosen Petronius Honoratus as their patron. His career began with the tres militiae: first as prefect or commander of Cohors I Raetorum, which was stationed at the time in Germania Inferior, followed by military tribune with Legio I Minervia also stationed in Germania Inferior, and lastly prefect of alaII Thracum Augusta pia fidelis, which was stationed in Mauretania Caesariensis. This concluded his military career. At this point Honoratus began his civilian career, probably after the beginning of the reign of Antoninus Pius. He became procurator monetae, or head of the imperial mint, which received an annual income of 100,000 sesterces. He advanced to procurator of the vicesima hereditatium, or overseer of the collection of the 5% inheritance tax, which received an annual income of 200,000 sesterces. This was followed with the appointment as procurator of the imperial properties in the provinces of Gallia Belgica and the two German provinces. Henriette Pavis d'Escurac notes he advanced to this posting without holding any governmental procuratorships, which is unusual: she compares his career to another eques, Gaius Junius Flavianus, was governor of Alpes Maritimes before advancing to procurator of imperial properties in Asturia and Galicia. Here Honoratus received a series of appointments to senior equestrian positions. D'Escurac agrees with Hans-Georg Pflaum's suggestion that the rapidity of his brilliant career may be partly explained by his kinship with Marcus Petronius Mamertinus, suffect consul in 150, and governor of Egypt before Honoratus. He returned to Rome to serve as procurator a rationibus, or head of the accounting section, and remained in Rome as annonae praefectus, or overseer of the grain supply for the capital city. Then Honoratus was appointed praefectus or governor of Egypt from 147 to 148; several primary sources attest to his presence there from August 29, 147 to November 11, 148. His presence as praefectus annone therefore is placed before 147. He assumed this post as the immediate successor of Lucius Valerius Proculus, who held the office from 144 to 146; he also was the immediate successor of Proculus in Egypt. Thus, as d'Escurac writes, Honoratus held the post of annonae praefectus between 146 and 147.
