Kostas Grammatopoulos was born in 1916 in Athens. He studied at the Athens School of Fine Arts (1934-1940), painting at the studio of Umberto Argyros, and printmaking under Yiannis Kefallinos. In 1940, he was among the young students who created some of the most famous posters for the Greek-Italian war and the same year he was awarded the Charalambos Chrysovergis prize. In 1942, he began to create woodcut prints of poets’ portraits and illustrations for the literary journal Nea Estia, as well as covers for books of literature. His work as an illustrator was significant: he illustrated over 100 books throughout his life. 

In 1949, after a tender invitation by the School Textbook Organization (OESV), he undertook the illustration and lithographic printing of the elementary school reading textbook, Ta Kala Paidia, which won first prize at the International Symposium on Education and the International Exhibition of Laeken (Belgium). In 1955, he illustrated the next reading textbook of the elementary school, Alfavitario, which would be used by students for over twenty years. 

In 1954, he went to Paris on a scholarship (State Scholarship Foundation), and continued his studies in painting, printmaking and graphic arts for three years (École des Beaux-Arts, École Estienne and École des Métiers d'Art). The Parisian experience affected his art decisively. His themes remained centered on Greece, but his style was enriched with characteristics of modern art.

After his first solo exhibition in Athens (Sarlat gallery, 1958), he was elected professor at the Athens School of Fine Arts (1959) and became head of the Printmaking Studio, as the successor of Yiannis Kefallinos. He taught until 1985, serving also as the School’s Director (1973-1975) and Dean (1978-1980).
He implemented his personal printmaking and printing techniques in his rich printmaking oeuvre, rendering colour and light with a poetic quality. His best known works are large coloured woodcuts on the Aegean landscape.

In 1968 he represented Greece at the 34th Venice Biennale and in 1972 he was awarded the Gold Medal of Printmaking at the Florence Biennale. In 1974 he created the emblem of the Greek Republic. His first retrospective exhibition was held at the Athens National Art Gallery in 1995. In 2007, four years after his death (Athens, 2003), his work was exhibited retrospectively at the Municipal Art Gallery of Thessaloniki.