He worked as a cashier, swim coach, and associate for a food importing company, but was forced to declare bankruptcy in 1925.
Having already published small volumes of lyric poetry in 1919 and 1923, he succeeded in a literary breakthrough in parody with the collection Mit fremden Federn in 1927.
Rudolf Walter Leonhardt later wrote in his obituary of Robert Neumann about his public success: "Two narrow bands have a lifetime of fifteen thick volumes buried.
After the occupation of Austria in 1938, he organized the "Free Austrian P.E.N.-Club" in London to assist writers threatened by Nazis to leave their country.
As editor and co-owner of the publishing house "Hutchinson International Authors," he initiated the publication of English translations of German writers in exile such as Arnold Zweig and Heinrich Mann.
He initiated the dismissal of the former PEN President Pierre Emmanuel and proposed the candidacy of Heinrich Böll, who was also elected in a vote.
In 1966 he published, in the leftist magazine Zeitschrift Konkret, a sharp polemic against the Group 47 and especially against Hans Werner Richter, Walter Höllerer and Günter Grass.
Neumann married Stefanie ("Stefie") Grünwald (1896–1975) in 1919 in Vienna, with whom he had a son named Henry Herbert ("Heini") (1921–1944).
In 1953 he married the German dancer Evelyn Milda Wally Hengerer (pseudonym: Mathilde Walewska, 1930–1958) with whom he had a son Michael Robert Henry (born 1955).