The 2013 Australian GT Championship was an Australian motor racing competition open to GT style closed production based sports cars which were either approved by the FIA for GT3 competition or approved by the Confederation of Australian Motor Sport (CAMS) as Australian GTs. It was sanctioned by CAMS as a National Championship with Australian GT Sportscar Group Pty Ltd appointed as the Category Manager. It was the 17th Australian GT Championship, the twelfth to be contested over a multi-event championship, and the eighth to be contested since the title was revived in 2005.

The Australian GT Championship is a CAMS-sanctioned national title for drivers of GT cars, held annually from 1960 to 1963, from 1982 to 1985 and from 2005. Each championship up to and including the 1963 title was contested over a single race and those after that year over a series of races. The categories which have contested the championship have not always been well defined and often have become a home for cars orphaned by category collapse or a sudden change in regulation.