Con O'Neill graduated in the 1980s with a BA majoring in Sociology & Political Science, followed by a Law Degree in Law in 1995, completing the Graduate Certificate in Legal Practice and thereafter was admitted to the Supreme Court of South Australia as a Barrister & Solicitor in 1996.
Upon graduating from Law, Con's first legal employment was in Housing Advocacy for 2 years. He then took the opportunity to hold the position of Principal Solicitor and Manager at Port Pirie Community Legal Service. He then worked a further year as the Managing Solicitor at the Wyong Community Legal Service in NSW.
Returning to Adelaide, Con worked for 7 years as a solicitor for the Aboriginal Legal Rights Movement in South Australia, including holding the position of Practice Manager of the Criminal Law Section.