- Amateur Record: 75 wins from 81 fights
- Katsidis fought as a Lightweight for the Australian Olympic Team at the 2000 Olympics in Sydney. Results were:
- Defeated Agnaldo Nunes (Brazil) 15-6
- Lost to Nurzhan Karimzhanov (Kazakstan) 7-9
Known as "Rocky", Katsidis turned pro in 2000, following the Sydney Olympiad. He debuted against Danny Wilson winning the Queensland state lightweight title. In his second bout he won the Australian lightweight title, the first boxer to so by his second fight. On February 17, 2007, Katsidis won the interim WBO Lightweight Title with a TKO win over Briton Graham Earl. That victory raised his pro record to 22 victories in 22 fights.
Katsidis landed eight months in prison for his part in a 2001 street brawl that saw the young fighter break another man's jaw. Katsidis refused to plead guilty, claiming self-defence, and received a 2-year sentence - reduced to 8 months - six months of which was spent in a high-security prison in Brisbane.