The Obelisk of Theodosius rests on an elaborately decorated base depicting Theodosius and his court at the Hippodrome of Constantinople. Underneath the main Proconnesian marble base (approximately 7 square meters) is another wider base with Greek and Latin inscriptions and hippodrome scenes. In addition, four bronze cubes support the corners of the obelisk, while four granite blocks are set between the corners of the upper base and lower base. The reliefs on the base constitute one of the most important dated pieces of late antique sculpture to survive. 
Reliefs on all four sides of the upper base show the emperor and his court attending the games. On each side, the reliefs are divided into two registers by a lattice balustrade that separates the upper tier of seating from the lower. The upper register on each side shows the kathisma – the imperial box at the Hippodrome which was linked with Great Palace. At the center of the upper register is the imperial group, which is flanked by two rows of figures: officials in the front row and Germanic guardsman at the back row. It is possible that these officials were individually portrayed, though it is impossible to confirm due to the current condition of the reliefs. The Germanic guardsmen wear torques around their necks, carry spears, and hold shields. The lower registers differ on each side of the base, with simple tiers of spectators on the southwester and northeastern sides. On the northeastern side, there are two standing attendants standing below the kathisma, next to an arched gateway. This arch gateway is depicted on the southwest side as well. 
On the northwestern side, there are four central figures, the largest is Theodosius, while on his left is the Western Emperor Valentinian II (19 years old in 390) and on the left, Arcadius and Honorius (then 13 and 6 years old). Its lower register depicts kneeling barbarians presenting gifts, which was perhaps meant to represent a barbarian embassy. On the southeastern side, the central figure is Theodosius, who stands with the victory wreath in his hand. The two smaller figures beside him are generally identifies as his sons Arcadius and Honorius, the future emperors of the Eastern and Western Roman Empire. On each side, there are several figures depicted in consular dress and holding the mappa – the white cloth dropped to signal the start of chariot race. The southeastern side, below the scene with Theodosius holding the victory wreath, has two tiers of spectators with a third tier of female dancers and musicians playing flutes and water organs.
There are also scenes from the hippodrome on the lower reliefs. On the northeastern side is a depiction of the erection of the obelisk. The northeast face of the obelisk is depicted lying on the ground in front of the Hippodrome’s colonnades. An official (possibly Proclus himself) is directly the workers, who attempt to raise the obelisk with ropes and windlasses. On its southwestern side, the obelisk stands erect on the spina of the Hippodrome, along with the Masonry Obelisk, the metae and perhaps the lap counter. There are four-horse chariots shown racing from left to right below the spina.  Above the spina are two figures riding on horseback, presumably victorious charioteers celebrating their victory on their chariot’s lead horse. 
In its original setting the obelisk and its base would have only been viewed from a distance in the seating of the Hippodrome and frequently obscured by chariots racing past. While its exact location in the Hippodrome is unknown, it is possible that the obelisk marked the center of the Hippodrome. Furthermore it is possible that the kathisma was directly in front of the obelisk, thus at the center as well.  The particular placement of the obelisk base seems to account for the language of the inscriptions: as Latin was the imperial language, it was oriented towards the emperor and his court on the southeastern side, while the circus factions, as representatives of the local Greek-speaking population, faced the Greek inscription on the northwestern side. The orientation of the reliefs on each side perhaps relates to the specific depictions as well.
All four reliefs are symmetrical, abstract, and hieratic, emphasizing Theodosius and the members of his dynasty. The age and seniority of the central figures, for example, are indicated by their size. The emperor's central position of the emperor, along the frontality of the images of the guards, prisoners, and spectators around him, suggests a ceremonial intent for the reliefs. A similar depiction of Theodosius and his court can be seen in the Missorium of Theodosius. The format for imperial representation developed earlier, as seen in the oratio and largitio registers in the Arch of Constantine, and continued later, as seen in the mosaics of Justinian and his entourage in San Vitale in Ravenna. These reliefs, then, can be viewed as a monumental counterpart to the late Roman panegyrics, delivered before the emperor at state occasions.
The imperial and triumphal character of the obelisk is also reinforced on every side of its base, thus emphasized the order and prosperity brought by imperial rule. This was particularly important following the Goths’ defeat of the Romans at the Battle of Adrianople in 378. The relief of Theodosius holding the victory wreath faced the imperial court, implying that all victors are dependent on Theodosius as the giver of victory and of its rewards. The cosmological significance of the obelisk and its circus context also can be seen in these reliefs. Just as the cosmic order is represented in the Hippodrome, so the imperial order is represented on the reliefs, which center of the emperor Theodosius.