After beginning his career in the civil service, Cuno helped organize Germany's food supply during the early years of World War I before he went to work for the Hamburg America shipping company in 1917.

He was the son of the administrative civil servant August George Wilhelm Cuno (1848–1915) and his wife Catherina Elisabeth Theresia, née Daske (1852–1878).

[1] During World War I, Cuno was involved in organizing food supplies for all of Germany, first directing the Imperial Grain Agency from its inception in early 1915 until July 1916.

He then was attached to State Secretary (i.e. Minister) Adolf Tortilowicz von Batocki-Friebe to help organize the War Office of Food (Kriegsernährungsamt).

After Ballin committed suicide in November 1918 in despair over Germany's defeat in World War I, Cuno was promoted to HAPAG's general director in December.

[1][2][4] Hopes were high that a government of experts, led by a man with excellent connections abroad, would make headway in the difficult talks with the Allies.

When Germany defaulted on its shipments of wood and coal (made as reparations in lieu of the gold currency that it lacked), the French declared it to be a deliberate breach of the agreements and on 11 January 1923 ordered its troops (later joined by Belgians) to occupy the Ruhr.

Reparation shipments to France and Belgium were stopped, the mines were told not to make any more deliveries to the countries, and civil servants and railroad personnel were instructed to disobey orders by the occupation authorities.

Financial support payments by the German government to the Ruhr businesses and to the inhabitants of the occupied zone affected by firm closures, deportations and arrests quickly added up to vast sums, mostly financed by printing money.

He was involved in negotiations about the release of German property impounded in the U.S. during the war and in working towards the merger with the Norddeutsche Lloyd shipping company, which took place in 1930.

[1] During the 1925 German presidential election, Cuno was outspoken in his support for Paul von Hindenburg, rather than the candidate of the Centre Party, Wilhelm Marx.