| Conventional Long Name: | Southeast Borneo Federation |
| Native Name: | Federasi Kalimantan Tenggara |
| Common Name: | Southeast Borneo |
| Subdivision: | Federation |
| Nation: | Indonesia |
| Status Text: | State-level autonomous region of Indonesia |
| P1: | Republic of Indonesia |
| Flag P1: | Flag of Indonesia.svg |
| S1: | South Kalimantan |
| Flag S1: | Flag of Indonesia.svg |
| Image Map Caption: | Southeast Borneo Federation in the United States of Indonesia |
| Era: | Cold War |
| Date Start: | January |
| Year Start: | 1947 |
| Date End: | 18 April |
| Year End: | 1950 |
Southeast Borneo Federation (Indonesian: Federasi Kalimantan Tenggara) was an autonomous area formed in the southeastern part of Indonesian island of Borneo by the Netherlands in 1948 as part of an attempt to re-establish the colony of the Dutch East Indies during the Indonesian National Revolution. Southeast Borneo became a constituent part of the United States of Indonesia in 1949. The Federation was dissolved on 18 April 1950 and combined with Great Dayak and Bandjar to form South Kalimantan Province.