RNZ reports Vice-President Kourabi Nenem at the sanctuary's launch said that the nation was committed to protecting sharks from exploitation and overfishing.
Kiribati has banned commercial shark fishing in the sanctuary, which is about the size of India.
Palau established the region's first shark sanctuary in 2009.
The Marshall Islands and Tokelau followed suit in 2011 and a year later French Polynesia and the Cook Islands created adjacent shark sanctuaries spanning almost 4 million square kilometres of ocean.
