Nicholas O'Halloran was a member of the Australian water polo team that won the bronze medal at the 2007 FINA Water Polo World League and the gold medal at the World Student Games in 2009, and represented Australia at the World Championships in Rome.
In January 2013, Mr O'Halloran became an investment banking analyst and associate with Merrill Lynch. He left in June 2017 to join Goldman Sachs, initially as an investment banking associate in its Perth office before moving to Sydney in January 2020 as an executive director. In January 2022, Mr O'Halloran relocated back to the firm's Perth office to help with WA resources client coverage.