| Conventional Long Name: | Republic of Tarnobrzeg |
| Common Name: | Tarnobrzeg |
| P1: | Kingdom of Galicia and Lodomeria |
| Flag P1: | Flag of Galicia-Lodomeria (1890–1918).svg |
| S1: | Second Polish Republic |
| Flag S1: | Flag of Poland.svg |
| Capital: | Tarnobrzeg |
| Common Languages: | Polish |
| Religion: | Catholicism |
| Government Type: | Republica |
| Era: | Aftermath of World War I |
| Date Start: | 6 November |
| Year Start: | 1918 |
| Year End: | 1919 |
| Date End: | Spring |
| Footnotes: | a. Soviet republic intended. |
| Leader Title1: | President |
| Leader Name1: | Tomasz Dąbal (last) |
| Today: | Poland |
The Republic of Tarnobrzeg (Polish: Republika Tarnobrzeska, pronounced as /pl/) was a short-lived political entity, proclaimed on 6 November 1918 in the Polish town of Tarnobrzeg. Its main founders were two socialist activists, Tomasz Dąbal and the Catholic priest Eugeniusz Okoń.
The idea of the Republic had its roots in mass demonstrations of peasants, which were taking place almost on a daily basis in the fall of 1918. Tarnobrzeg had been part of Austria-Hungary (Kingdom of Galicia and Lodomeria) and the dissolution of this entity created a political unrest. On 6 November, after a demonstration with some 30,000 people, local peasants decided to take advantage of it and seize power.
As news of the Russian Revolution came to Tarnobrzeg, socialist activists decided to follow Communist ideas. They demanded the liquidation of capitalist government and the introduction of a land reform, which would result in taking away land from rich owners and giving it to the poor peasantry. Also, directed by Okoń and Dąbal, the peasants started to organize local administration as well as a peasants' militia.
The Republic of Tarnobrzeg was suppressed by units of the freshly created Polish Army at the beginning of 1919. Father Okoń was arrested but soon released, when the locals elected him to the Polish Parliament.