Antoniou was born on April 19, 1961 in Galatsi, Athens. He joined Panathinaikos in 1977, making his debut in the first team at age 16. For two seasons (1982, 1983) he played for Apollon Athens rejoining Panathinaikos the following year. He stayed with the greens until 1994, ending his career at Athinaikos the following year.
Altogether, he participated in 385 League games.
- In the summer of 1988, Antoniou was found to have negotiated his transfer with Giorgos Koskotas to join Olympiakos. His agreement was found to be illegal by the sports authorities of Greece as Panathinaikos had the right to make the first offer to the player to renew his contract and the right to match any counteroffers made by another club. Thus, Antoniou remained with Panathinaikos.