He spent his early years in Switzerland and Istanbul, where his father was director general of the Ottoman Bank.
He obtained a BA in economics and in 1951 the degree of the École pratique des hautes études (historical and philological studies section).
In 1958, Paul Garelli joined the Centre national de la recherche scientifique where he became a research fellow in 1967 at the head of the Archaeology and history section of the Assyrian-Babylonian countries.
Paul Garelli was a member of the Société Asiatique (1972) and of the international committee of Ebla (Rome) (1977) and president of the François Thureau-Dangin group (1975).
In 1982, he was elected ordinary member of the Académie des Inscriptions et Belles-Lettres then, in 1986, professor of Assyriologie at the Collège de France.