Ševčenko has contributed to two connected yet distinct disciplines, Byzantine, Slavic studies, and Ukrainian Studies. His work addresses Byzantine written culture and society from the Late Antique period to the 15th century and explores contact between the Slavic world and Byzantium from the medieval to the early modern period. Ševčenko has written on philology, literature, epigraphy, paleography and codicology. He was noted for the engaging, "detective novel" style of his prose, as in his famous article “The Date and Author of the So-Called Fragments of Toparcha Gothicus”, which reveals that the text considered the earliest surviving narrative source on the history of the Kievan Rus’ is a 19th-century forgery crafted by its “discoverer” and editor Carl Benedict Hase. Ševčenko's approach was noted for its extensive engagement with primary source material, not simply as edited texts but as original manuscripts. He uses these sources to elucidate key issues in Byzantine and Slavic studies, such as the evangelizing mission of Cyril and Methodius among the Slavs, Byzantine political ideology and its reception in the Slavic world, and the Zealot uprising in 14th century Thessaloniki. His most recent publication was an edition and English translation of the only extant secular biography in Byzantine literature, that of the life of the 9th century emperor Basil I, which was written by scholars associated with Basil's grandson, Emperor Constantine VII. Basil's biography is a major source for the political and cultural history of Byzantium and its neighbors in the 9th and 10th centuries.
''Animal Farm''
While working with displaced Ukrainian persons after World War II, Ševčenko wrote to George Orwell and received permission to translate Animal Farm into Ukrainian, one of the first translations of the book. Orwell agreed, waving his royalties and also writing a detailed preface for the edition.
Ševčenko's law
Ševčenko's law or Ševčenko's law of the dog and the forest is the tendency of historians to repeat the coverage and the work of previous historians, to the disadvantage of general historical coverage. The situation is compared to a dog and a forest. A dog going into a virgin forest picks a tree at random, and urinates against it. Despite the tree having no intrinsic outstanding attraction as an object for urinating against, other dogs subsequently entering the same forest will show a tendency to urinate against the same tree.
Awards
Antonovych prize - Scientific Award of the International Foundation of O. and T. Antonovich for the study "Ukraine between East and West".
Publications
Ihor Ševčenko, Études sur la polémique entre Théodore Métochite et Nicéphore Choumnos. ASIN: B000KJ9U8O
Ihor Ševčenko, Society and Intellectual Life in Late Byzantium ,
Ihor Ševčenko, Ideology, Letters and Culture in the Byzantine World
Ihor Ševčenko, Byzantium and the Slavs in Letters and Culture ,