The 9.7in (24.6cm) computer is 7.5mm (0.3in) thick and weighs 1lb (469g), which the firm claims is the
lightest full-sized tablet on the market.
It is powered by the same A7 chip found in the company's iPhone 5S.
The launch comes at a time when some analysts have suggested that Google's Android is about to overtake Apple's iOS as the bestselling tablet platform.
Apple also announced a new version of its iPad Mini.
Its 7.9in (20cm) screen has been upgraded to feature 2048 by 1536 pixels - the same as the larger model. It is being branded as "retina" to highlight the increased resolution.