奥兰治河（英语：Orange River，南非语：Oranjerivier、纳马语：Nu Gariep、索托语：Senqu），又译作奥伦治河，是南非最大的河流，长2,200公里，流域面积973,000平方公里。

起源于莱索托和南非共和国交界地区，大致往西流，在南非和纳米比亚的边界流入大西洋。主要支流有瓦尔河等。

The Orange River (Afrikaans/Dutch: Oranjerivier), Gariep River, Groote River or Senqu River is the longest river in South Africa. It rises in the Drakensberg mountains in Lesotho, flowing westwards through South Africa to the Atlantic Ocean. The river forms part of the international borders between South Africa and Namibia and between South Africa and Lesotho, as well as several provincial borders within South Africa. Except for Upington, it does not pass through any major cities. The Orange River plays an important role in the South African economy by providing water for irrigation, as well as hydroelectric power. The river was named by Robert Jacob Gordon after the Dutch Royal House.