Casey Vincent first made a name for himself as an international athlete at the 1998 World Junior Championships where he winning silver as an individual and gold in the relay. He then made his Olympic debut at the Sydney 2000 Games, competing in the 400m and 4x400m relay. Vincent's individual event saw him finish sixth in the semi-final with a time of 45.61, 11th overall. Vincent teamed up with Patrick Dwyer, Michael Hazel and Blair Young to compete in the relay. Vincent contested the qualifier and semi-final however due to injury, Brad Jamieson replaced him in the final, the team finishing eighth. At the Athens 2004 Olympic Games, Vincent placed fourth in the qualifying round of the men's 400m, missing a semi-final berth.