Uku or UKU may refer to:
- Ukko or Uku, god of sky, weather, crops (harvest) and other natural things in Estonian and Finnish mythology
- Uku (given name), Estonian masculine given name
- UK Ultraspeed, proposed magnetic-levitation train line between London and Glasgow
- Places
- Uku, Angola, town in Angola
- Uku, Nagasaki, town in Kitamatsuura District, Nagasaki, Japan
- Uku, Nepal, village development committee in Darchula District, Mahakali Zone, Nepal
- Uku, Sudan
- Uku, Estonia, village in Kadrina Parish, Lääne-Viru County, Estonia
- Uku River, river in the Democratic Republic of the Congo