| Conventional Long Name: | State of the Republic of Indonesia |
| Native Name: | Indonesian: Negara Republik Indonesia |
| Common Name: | Indonesia |
| Subdivision: | Federation |
| Nation: | Indonesia |
| Status Text: | State of Indonesia |
| Today: | Indonesia |
| Image Map Caption: | The United States of Indonesia. The State of the Republic of Indonesia is shown in red. |
| Government Type: | Federated republic |
| Title Leader: | President |
| Leader1: | Assaat |
| Year Leader1: | 1949–1950 |
| Title Deputy: | Prime minister |
| Year Deputy1: | 1949–1950 |
| Deputy2: | Abdul Halim |
| Year Deputy2: | 1950 |
| Capital: | Yogyakarta |
| Era: | Cold War |
| Event Start: | Established as component state of RUSI |
| Date Start: | 27 December |
| Year Start: | 1949 |
| Event End: | Unitary republic formed |
| Date End: | 17 August |
| Year End: | 1950 |
The State of the Republic of Indonesia (Indonesian: Negara Republik Indonesia, old spelling: Indonesian: Negara Repoeblik Indonesia,) was a federated state Indonesian: (negara bagian) of the United States of Indonesia (RUSI) which was established on 27 December 1949. The territory of the state included parts of Java and most of Sumatra, and its capital was Yogyakarta. The acting president of the Republic was Assaat (Sukarno became president of the RUSI) and the prime minister was first Susanto Tirtoprodjo until 16 January 1950, then Abdul Halim. On 17 August, the United States of Indonesia ceased to exist as the last of the component states dissolved themselves into a unitary Republic of Indonesia encompassing the entire territory of the former Dutch East Indies except for West Papua.
Assaat Datuk Mudo was the only president of this Yogyakarta-based republic