| Competition: | Segunda División |
| Season: | 1999–2000 |
| Winners: | UD Las Palmas |
| Promoted: | UD Las Palmas CA Osasuna Villarreal CF |
| Relegated: | CP Mérida Atlético Madrid B CD Logroñés CD Toledo |
| League Topscorer: |  Paco Salillas |
| Matches: | 462 |
| Total Goals: | 1058 |
| Prevseason: | 1998–99 |
| Nextseason: | 2000–01 |
The 1999–2000 Segunda División was the 69th edition since the establishment of the competition.
22 teams participated in the league. The teams that promoted to La Liga were UD Las Palmas, Osasuna and Villarreal CF. The teams that relegated to Segunda División B were CP Mérida, Atlético de Madrid B, CD Logroñés and CD Toledo.
| Autonomous community | Number of teams | Teams | |
|---|---|---|---|
| 1 | 3 | Badajoz, Extremadura, Mérida | |
| 3 | Atlético Madrid B, Leganés, Getafe | ||
| 3 | Elche, Levante, Villarreal | ||
| 4 | 2 | Córdoba, Recreativo | |
| 2 | Las Palmas, Tenerife | ||
| 2 | Albacete, Toledo | ||
| 7 | 1 | Sporting | |
| 1 | Eibar | ||
| 1 | Salamanca | ||
| 1 | Lleida | ||
| 1 | Compostela | ||
| 1 | Logroñés | ||
| 1 | Osasuna | ||