Though he also wrote Romana, a book about the history of Rome, his most known work is his Getica, written in Constantinople  about AD 551  . His work is the only remaining classical work dealing with the early history of the Goths.
Jordanes was asked by a friend to write this book as a summary of a multi-volume history of the Goths (now lost) by the statesman Cassiodorus. Jordanes was selected chiefly for his interest in history (he was working on a history of Rome), his ability to write succinctly, and because of his own Gothic background. He had been a high-level notarius, or secretary, of a small client state on the Roman frontier in Moesia, modern northern Bulgaria  .
Other writers, e.g. Procopius, wrote extant works on the later history of the Goths. As the only surviving work on Gothic origins, Jordanes' Getica has been the object of much critical review. Jordanes wrote in late Latin, denigrated by Classicists for its non-conformance to the rules of classical Ciceronian Latin. According to his own introduction, he only had three days to review Cassiodorus' work; thus, he must have been relying on his own knowledge. Some of his statements are very succinct.
Jordanes writes about himself almost in passing:
The Sciri, moreover, and the Sadagarii and certain of the Alani with their leader, Candac by name, received Scythia Minor and Lower Moesia. Paria, the father of my father Alanoviiamuth (that is to say, my grandfather), was secretary to this Candac as long as he lived. To his sister's son Gunthigis, also called Baza, the Master of the Soldiery, who was the son of Andag the son of Andela, who was descended from the stock of the Amali, I also, Jordanes, although an unlearned man before my conversion, was secretary.
Already in the Mommsen text edition of 1882 it was suggested that the very long name of Jordanes' father should be split into two parts: Alanovii Amuthis, both genitive forms. Jordanes' father's name would then be Amuth. The preceding word should then belong to Candac, signifying that he was an Alan. Mommsen, however, dismissed suggestions to emend a corrupt text .
Paria was Jordanes' paternal grandfather. Jordanes writes that he was secretary to Candac, dux Alanorum, an otherwise unknown leader of the Alans.
This was ante conversionem meam ("before my conversion"). The nature and details of the conversion remain obscure. The conversion was probably not from paganism to Christianity. The Goths had been converted with the assistance of Ulfilas (a Goth), made bishop on that account. However, the Goths had adopted Arianism. Jordanes' conversion may have been a conversion to the trinitarian Nicene creed, which may be expressed in anti-Arianism in certain passages in Getica  . In the letter to Vigilius he mentions that he was awakened vestris interrogationibus - "by your questioning".
Alternatively, Jordanes' conversio may mean that he had become a monk, or a religiosus, or a member of the clergy. Some manuscripts say that he was a bishop, some even say bishop of Ravenna, but the name Jordanes is not known in the lists of bishops of Ravenna.
Jordanes wrote his Romana at the behest of a certain Vigilius. Although some scholars have identified this person with pope Vigilius, there is nothing else to support the identification besides the name. The form of address that Jordanes uses and his admonition that Vigilius "turn to God" would seem to rule out this identification .
In the preface to his Getica, Jordanes writes that he is interrupting his work on the Romana at the behest of a brother Castalius, who apparently knew that Jordanes had had the twelve volumes of the History of the Goths by Cassiodorus at home. Castalius would like a short book about the subject, and Jordanes obliges with an excerpt based on memory (and notes, one must assume), possibly supplemented with other material he had access to. The Getica sets off with a geography/ethnography of the North, especially of Scandza (16-24). He lets the history of the Goths commence with the emigration of Berig with three ships from Scandza to Gothiscandza (25, 94), in a distant past. In the pen of Jordanes (or Cassiodorus), Herodotus' Getian demi-god Zalmoxis becomes a king of the Goths (39). Jordanes tells how the Goths sacked "Troy and Ilium" just after they had recovered somewhat from the war with Agamemnon (108). They are also said to have encountered the Egyptian pharaoh Vesosis (47). The less fictional part of Jordanes' work begins when the Goths encounter Roman military forces in the third century AD. The work concludes with the defeat of the Goths by the Byzantine general Belisarius. Jordanes concludes the work by stating that he writes to honour those who were victorious over the Goths after a history of 2030 years.