Arenigobius bifrenatus(Kner 1865) is a burrowing coastal and estuarine goby from temperate areas of Australia. One specimen was captured from the Whangateau Harbour, north‐eastern New Zealand, on 1 April 1998, constituting the first record of this species from New Zealand. Further intensive beach seining at Pollen Island, within the Waitemata Harbour (Auckland), yielded two further specimens which were females in breeding condition. We suggest that the species is an adventive, and its presence in northern New Zealand waters is the result of accidental transport in shipping ballast water.