Joadja is a historic town, now in ruins, in the Southern Highlands of New South Wales, Australia, in Wingecarribee Shire. The remnants of the town were added to the New South Wales State Heritage Register on 5 November 1999.

The Southern Highlands, also locally referred to as the Highlands, is a geographical region and district in New South Wales, Australia and is 110 km south-west of Sydney. The region comprises the local government area of the Wingecarribee Shire and also towns of the Mulwaree Shire. The region is also considered a wine region.