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, former union territory of India, now part of Dadra and Nagar Haveli 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