Born in Bucharest, his parents were Petre Rosetti Bălănescu, a lawyer and landowner, and his wife Zoe (née Cornescu), whose father wrote the 1874 Manualul vânătorului, prefaced with Pseudo-cynegeticos by Alexandru Odobescu.

On scholarship in Paris from 1920 to 1928, he first attended the École pratique des Hautes Études, completing the program with a 1924 thesis on rhotacism in Romanian.

[1][2] In 1944, during World War II, he was among the signers of a memorandum urging the Ion Antonescu regime to withdraw Romania from fighting alongside the Axis powers.

[5] Although an unhesitating adherent to the ruling party—indifferent to a succession of dictatorships, he was primarily concerned with using them to the advantage of his studies—his liberal Europeanism caused him to be excluded from the university between 1951 and 1954, a period of high Stalinism.

In the field of literature, he was among the foremost editors of the interwar period and lent support to numerous authors, and also an anthologist (Cronicarii români, 1944; Schiță de istorie socială a limbii române, 1975).

Esquisse d'un théorie générale (1943; published in Romanian as Filosofia cuvântului, 1946); Istoria limbii române literare, vol.

In 1977, Rosetti published his correspondence with George Călinescu, revealing his role in the composition of the latter's 1941 magnum opus, Istoria literaturii române de la origini până în prezent.