Holden introduced a retractable hard-top version for the Astra in 2007 based on the European Opel/Vauxhall Astra TwinTop.
Before the financial crisis, the car market was thriving, and the carmakers tried to attract more people to their showrooms with low-interest loans and attractive bodyworks. The era of hard-top cabriolets was also rising, and Opel considered building one as an alternative for the already available rag-top model. Holden, from Australia, was eager to get its hands on the new model and received approval from GM to sell it.

The Astra TT kept the same front fascia from the Astra J generation. The raked A-pillars were similar to those on the GTC version but thicker since they acted as a roll-over protection system. The Astra TT was reinforced and achieved a 30% higher rigidity than a standard convertible to make the car safer. At the back, the trunk was easy to access due to an intelligent system that allowed the roof to be raised and allow storage.

Inside, there was room for four adult passengers, but with limited legroom for the rear ones. Holden carried over the front seats from the Astra GTC model.

Under the hood, the Astra TT took only a few engines from the Astra line-up, but fortunately, it took the more powerful ones. The base version was the 115 hp naturally aspirated unit, while the most potent engine provided 200 hp. A 150 hp diesel version was available as well.