Diu may refer to:
- Diu, India, a city in Diu district in the union territory of Dadra and Nagar Haveli and Daman and Diu, India
- Diu district, part of the union territory of Dadra and Nagar Haveli and Daman and Diu
- Diu Island, an island and part of Diu district
- Daman and Diu (Lok Sabha constituency)
- Daman and Diu, former union territory of India, now part of Dadra and Nagar Haveli and Daman and Diu
- Goa, Daman and Diu, former union territory of India, divided into Goa and Daman and Diu
- Diu Head, a headland in the Arabian Sea
- Diu (Cantonese), a Cantonese profanity
- Buth Diu (died 1972), Sudanese politician
DIU may refer to:
- Dansk Interlingua Union, an organization that promotes Interlingua in Denmark
- Defense Innovation Unit, a US Department of Defense organization
- Diplôme interuniversitaire, a French degree
- Diu Airport, in Diu, India, IATA code: DIU
- Divisional Intelligence Unit, police intelligence at the divisional level
- Down-with-Imperialism Union, a union formed by Kim Il-sung, president of North Korea
- Dresden International University, part of Dresden University in Germany
- Dubrovnik International University in Croatia
- Diamond Is Unbreakable, the fourth part of manga series JoJo's Bizarre Adventure
- Daffodil International University in Bangladesh