Theophanes's Chronicle covers the period from 284, where the Chronicle of George Synkellos ends, until 813. Theophanes's chronicle presents itself as a continuation of the history of George Synkellos. Theophanes explains that George had asked him to complete the task of compiling the history and had given Theophanes the materials he had gathered. How far Theophanes should be credited with the authorship of his chronicle has been a matter of scholarly debate.

It is one of few Byzantine texts that is a true chronicle, in that it enumerates every year, and lists events for each year. The entry for each year begins with a listing of the year of the world, the year since the Incarnation, the regnal year of the Roman Emperor, the Persian Emperor, and the bishops of Rome, Constantinople, Jerusalem, Alexandria, and Antioch. After the conquest of the Persian Empire, it uses years of the rulers of the Arabs in place of the Persian Emperors. Despite the impression of chronological accuracy, many of these dates are mistaken. Scholars also debate whether these dates were integral to Theophanes's original Chronicle or were added by a later copyist.

The coverage of events is uneven and sometimes thin. For periods in which he has good source material Theophanes may write several pages per year but for eras in which he is less well- informed, his entries are very short. For instance, his Chronicle contains only the listing of regnal dates for each year for 305– 308. He includes significant information about developments about the seventh century Arab conquests and the development of the Arab polity.

In the portions of his Chronicle from 284 until the advent iconoclasm in the middle of the eighth century, Theophanes does not insert his own authorial voice into his text significantly. He seems to be fairly impartially marshaling evidence, occasionally labeling an emperor as pious or impious but otherwise not inserting his value judgments into the history. Beginning with the iconoclast controversy in the reign of Leo III (717– 741) however, he becomes deeply emotionally invested in telling a markedly moralizing story, in which his hatred of the iconoclast emperors is manifest. These sections sometimes read like an anti- iconoclast pamphlet and show more engagement in creating a rhetorically effective history.