| Augustin Dumon-Dumortier | |
| Office: | President of the Senate |
| Term Start: | 27 June 1848 |
| Term End: | 28 January 1852 |
| Predecessor: | Louis de Schiervel |
| Successor: | Eugène de Ligne d'Amblise et d'Epinoy |
| Birth Date: | 4 December 1791 |
| Birth Place: | Lille, France |
| Death Place: | Tournai, Belgium |
| Party: | Liberal Party |
Augustin Aimable Dumon-Dumortier (4 December 1791 – 28 January 1852) was a Belgian industrialist, diplomat and liberal politician.
Born at Lille, he was President of the Belgian Senate from 27 June 1848 until 28 January 1852, governor of the province of Hainaut and burgomaster of Tournai. In 1849, he was sent to the Netherlands as a special envoy to congratulate William III upon his coronation. This was 19 years after the Belgian Revolution, which had made an end to the United Kingdom of the Netherlands.
He was a chevalier de l'ordre de Leopold, and he received the Dutch grand-croix de l'ordre de la Couronne de Chêne.
Dumon-Dumortier died at Tournai in 1852.