Born in Elliniko, Ioannina, in 1942, he studied at the Athens School of Fine Arts on a scholarship, next to Yiannis Pappas (1961-1966).

In 1967 he studied ancient Greek Art and the Art of the Mediterranean Basin, on a two-year domestic Scholarship from the Government Scholarship Service (I.K.Y). His Mediterranean journeys took him to Egypt, Asia Minor, Cyprus, South Italy and Sicily.

In 1970 he became assistant Professor at the Athens School of Fine Arts, next to Y. Pappas.

From 1981 to 1982, during his post-graduate studies at the École Nationale Superieure des Arts Appliques et des Metiers d' Art in Paris, he studied the modern sculpture materials.

In 1996-1997 he visited the USA, on a 6-month sabbatical, in order to study the educational programs and the organization of sculpture workshops at the N.Y. School of Fine Arts.

Through the Erasmus-Exchange programs he regularly co-organizes Workshops in association with the Hdk Berlin and the art schools of Brera and Bolognia.

During the last 20 years Th. Papayiannis has initiated the organization of Sculpture Symposiums in many Greek towns and Cyprus, creating large scale sculptures for public spaces. The sculptures are being created on-site.

He has been actively involved in 30 individual and numerous group exhibitions, both in Greece and abroad.

His monumental works are found in many private spaces, museums and private collections, both in Greece and abroad.

He has created many busts, statues of significant personalities, medals and coins, as well as huge sculptural compositions placed in public and private spaces.

He has been awarded many prizes at various competitions, last of them being the international competition for a sculpture at the Chicago airport.

His work has been the subject of articles in newspapers and magazines, as well as radio and television programs both in Greece and abroad.

Papayiannis is currently Professor of Sculpture at the Athens School of Fine Arts.

He lives and works in Athens, Greece.