Born in Thessaloniki, Kostas Yiavis earned a bachelor's degree in English and a master's in critical theory at the University of Thessaloniki before moving to Cambridge for a master's in medieval and Renaissance Literature, and a PhD in Greek literature. He then went to the United States where he taught Modern Greek language and literature at Cornell, served a post-doctoral stint at Princeton, and was a Byzantine Fellow at Harvard’s Dumbarton Oaks. He returned to Europe as a Visiting Professor of Modern Greek in Hamburg where he had been a Humboldt Fellow. Earlier in 2014 he took up the post of Ἐπίκουρος Καθηγητής (Assistant/early Associate Professor) of Modern Greek and Comparative Literature at the Faculty of Greek in Thessaloniki.

Yiavis is a literary critic with interest in all expressions of Greek from the Middle Ages to the present. Much of his initial work explored areas which are central to Greek and European literature, especially in early modernity. His first book, a critical edition of Imperios and Margarona, sought to integrate early Modern Greek romance with the Western European, Mediterranean and Near Eastern traditions. It made the case that cultural exchange was the unacknowledged norm during the long emergence into Greek modernity.

Yiavis's current research emphasises not only the impact of the Greek thought world, and the (largely uncharted) external influences it has absorbed, but also the tensions within the Western and Eastern traditions. Yiavis is interested in the revolutionary cultural changes that energize what we usually call periods. He sees literature as an integral part of cultural history, combined with political culture, collective identities and the history of ideas.

For many years Yiavis was the review editor of the Anglo-Hellenic Review. He is a strong believer in civic responsibility, has a keen interest in public policy, and is a supporter of the boards and advisory councils of a number of think tanks.