Ölgii (Mongolian: Өлгий, Kazakh: Өлгей) may signify:
- Ölgii Uul, a mountain in the Tavan Bogd massif in the extreme west of Mongolia
- Bayan-Ölgii Province, an aimag of Mongolia
- Ölgii (city), the capital of Bayan-Ölgii aimag
- Ölgii Airport, the airport of Ölgii city
- Ölgii, Uvs, a sum (district) of Uvs aimag