His parents were deported and eventually died in Nazi labor camps; Celan himself was confined for eighteen months in a Romanian labor-camp before escaping to the Red Army.

In 1945, he moved to Bucharest and became friends with many of the leading Romanian writers of the time, witnessing the last flowering of Romanian surrealism. He worked as a reader in a publishing house and as a translator. He also began to publish his own poems and translations under a series of pseudonyms. In 1947 he settled on the pseudonym Celan-an anagram of Ancel, the Romanian form of his surname. He lived briefly in Vienna before settling in Paris in 1948 to study German philology and literature. He took his Licence des Lettres in 1950, and in 1952 he married the graphic artist Gisèle de Lestrange. They had a son, Eric, in 1955.

Celan's first book was published in 1947; it received very little critical attention. His second book, Mohn und Gedächtnis [Poppy and Memory], however, garnered tremendous acclaim and helped to establish his reputation. Among his most well-known and often-anthologized poems from this time is "Fugue of Death." The poem opens with the words "Black milk of daybreak we drink it at evening / we drink it at midday and morning we drink it at night" and goes on to offer a stark evocation of life in the Nazi death camps.

In 1959, Celan took a job as a reader in German Language and Literature at the École Normale Supérieure in Paris, a position he would hold until his death in 1970. His poems from this period grew shorter, more fragmented and broken in their syntax and perceptions. In 1960 he received the Georg Büchner Prize. During the 1960s he published more than six books of poetry and gained international fame. In addition to his own poems, he remained active as a translator, bringing out works from writers such as Henri Michaux, Osip Mandelstam, René Char, Paul Valéry, and Fernando Pessoa. In 1970, Celan committed suicide. His position in German-language poetry is best read from the fact that there have been only six poets to whom leading German philosophers have devoted studies: Goethe, Novalis, Hölderlin, Rilke, Trakl, and Celan (Dilthey wrote on Goethe, Novalis, and Hölderlin, Heidegger on Hölderlin, Rilke, and Trakl, and Gadamer on Celan).