August Karl Graf von Dönhoff-Friedrichstein (26 January 1845 – 9 September 1920) was a Prussian nobleman, diplomat and politician.

Like his father, Dönhoff also embarked on a diplomatic career and worked as secretary of legation for the Empire in Paris, Vienna, London, Saint Petersburg and Washington.

In Washington he made friends with the Interior Minister Carl Schurz and accompanied him on an adventurous journey to the American West.

Dönhoff laid down his diplomatic duties when, after his father's death in 1874, he took over his hereditary seat in the Prussian House of Lords.

In 1917 August von Dönhoff was one of the founding members of the German Fatherland Party, which advocated a perseverance policy and a peace of victory in the First World War.