Holly started her water polo career at 13 years old after then high school teacher and Olympic gold medal winner Debbie Watson encouraged her to try out. As a Junior, she was a member of the team that won gold at the World Women’s Junior Water Polo Championships in 2007 in Porto, Portugal. 

Holly was selected for the Stingers water polo squad for the London 2012 Olympics who won bronze, and she went on to compete at the Rio 2016 Olympics placing sixth.  She and her sister Emma are the first siblings to have represented Australia in the summer and winter Games, with Emma competing in the Vancouver 2010 Winter Games.

In addition to competing in the Olympics, Holly represented Australia from 2009 to 2016 with the Stingers making the following podium finishes:

• Silver at the 2015 Women’s Water Polo World League Intercontinental Preliminary Tournament in Auckland, NZ 
• Silver at the 2016 Women’s Water Polo World League Intercontinental Preliminary Tournament in Lewisville, USA 
• Bronze at the 2016 Women’s Water Polo World League Super Final in Shanghai, China
• Silver at the 2015 Women’s Water Polo League Super Final in Shanghai, China
• Silver at the 2015 Women’s Water Polo World League Intercontinental Preliminary Tournament held in Auckland, NZ 
• Silver at the 2015 Women’s Water Polo World League Intercontinental Preliminary Tournament held in Auckland, NZ 
• Silver at the 2013 World Championships held in Barcelona, Spain 
• Bronze at the 2011 Women’s Water Polo World League Super Final in Tianjin, China 
• Silver at the 2010 Women’s Water Polo World Cup held in Christchurch, New Zealand
• Bronze at the 2009 Women’s Water Polo World League held in Kirishi, Russia.