Its main founder was the Greek diplomat and bibliophile Joannes Gennadius (1844–1932), who initially donated part of his collection to the newly founded National Library of Greece.
Returning to Athens a few years later he was distraught to discover they had no reference to his donated items, and so he resolved to find a better home for his collection.
While attending the Washington Naval Treaty, American scholars showed interest in founding a dedicated facility in Greece.
A dedicated neoclassical building was built, with financial support from the Carnegie Corporation, to house the 26,000 volumes donated by Gennadius.
The building was designed by the New York firm of Van Pelt and Thompson, in the style of a classical temple with gardens.