Antoniu is a given name and a surname. Notable people with this name include the following:
Given name
- Antoniu Buci (born 1990), Romanian weightlifter
- Antoniu Vasile (born 1942), Romanian boxer
Surname
- Costache Antoniu (1900–1979), Romanian actor
- Kristaq Antoniu, also known as Cristache Antoniu, (1907 – 1979), Romanian singer and actor