Controlling the entire public machinery, the emperor was at the top of the Byzantine Empire administrative hierarchy. Whereas in Roman years the Empire was divided in large provinces governed by the Senate or imperial commissioners, in early Byzantine times there were very few administrative districts, called eparchotites. Provincial administration in Early Byzantine Period was divided into 120 provinces, which in the 4th century were divided into 15 commands and these in turn into four large administrative units. A praetorian prefect was in charge of each administrative unit, the vicar of each command - an office abolished by Justinian - and the archon of each province. These were all high-ranking public officials with administrative, juridical, financial and legal authorities.

A group of agencies performed the central administration of the Empire, presided over by the magister officiorum. The imperial post, guard, court events, communication with foreign diplomatic missions as well as control of the borders, public road transportation and control of commanders in frontier territories, all were part of the jurisdiction of this single person. He also oversaw the command of the center and of the provinces.

An experienced legislator, quastor sacri palatii was today's minister of justice, assisting the emperor in legislative and juridical duties.

The komes sacrum largitionum, the count of sacred largesse, was in charge of the fiscal sector. The komes rerum privatarum was responsible for royal real estate property. In charge of court services, the praepositus sacri cubiculi was an important officer who rose above the other four in hierarchy since the 5th century.

The command of Constantinople was assigned to the eparch of the city - an office that already existed in Rome. His responsibilities were similar to those of today's mayors, and they expanded over time to include juridical duties as well as the control of commerce and professional organizations.

A characteristic feature of Byzantine administration was that many authorities were concentrated in the hands of a few people, which made it difficult to monitor them. That is why many independent agencies with limited authorities were established in the 6th century. Moreover, Justinian encouraged the militarization of public administration in the provinces.