In 1994, McCormack and Fiona Wakefield founded the first female law firm in Christchurch.[1] In 2003 the firm merged with Simon Mortlock Partners to become Mortlock McCormack Law. McCormack specialised in commercial and corporate law and had a key role in the development of the central city project The Terrace following the 2010–2011 Canterbury earthquakes.[2]
In 2013 she was appointed pro-chancellor of the University of Canterbury, and in 2019 she left Mortlock McCormack after taking up the position of chancellor.[3]
McCormack has also held a number of directorships, including Lyttelton Port Company from 1998 to 2007, the New Zealand Symphony Orchestra from 2003 to 2008, KiwiRail and she is a board member of Public Trust. She is also a member of the New Zealand Law Society and the Institute of Directors in New Zealand.[1]