Antonio was admitted to practice as an attorney in 1996. His first exposure to personal injury law was in Durban in 1999, when he worked for a leading personal injury law firm in Durban. In 2001 Antonio joined the Shipman Inquiry in Manchester as an assistant to the Solicitor to the Inquiry. Antonio was tasked with gathering, analyzing and preparing evidence for the Inquiry for presentation to the chairlady, Dame Janet Smith DBE.

In 2002, after being admitted to practice as a Solicitor in England and Wales, Antonio joined Halliwell Landau (then a top 50 Law Firm in England) at their Manchester Offices, working in their Insurance department, defending personal injury claims. He represented some of the biggest Insurance Companies in England including, Norwich Union, XL Winterthur (now XL Group) and American Insurance Group. Antonio dealt with Injury on Duty matters, especially occupational diseases representing clients in the County Courts and the High Courts.

In 2004, Antonio returned to South Africa and started AC DE SOUSA ATTORNEYS. Specializing in all personal injury claims.