| Ágoston Valentiny | |
| Order: | Minister of Justice of Hungary |
| Term Start: | 22 December 1944 (officially 28 March 1945) |
| Term End: | 21 July 1945 |
| Predecessor: | László Budinszky |
| Successor: | István Ries |
| Birth Date: | 6 October 1888 |
| Birth Place: | Kalocsa, Austria-Hungary |
| Death Place: | Budapest, People's Republic of Hungary |
| Profession: | politician, jurist |
| Party: | MSZDP |
Ágoston Valentiny (6 October 1888 – 21 August 1958) was a Hungarian politician and jurist, who served as Minister of Justice in the Interim National Government. He was born into a working-class family with six children. His father was a machine fitter and engineer. Valentiny finished his law studies in Kolozsvár. He joined the Hungarian Social Democratic Party on 1 January 1919. During the German occupation in 1944 he was interned. After the "Liberation" of Szeged he became mayor of the town. He was a member of the Interim National Assembly.
After the 1945 elections he had to resign from the ministerial position because of the communists' attacks. After that he worked as a lawyer. He was arrested and sentenced in a show trial in 1950. He was set free after five years. After his death he was rehabilitated.