Rakitū Island in the Hauraki Gulf has been declared predator free.
A check by predator-seeking dogs last week confirmed rats have been removed from the 300-hectare, off the coast of Great Barrier Island, Conservation Minister Eugenie Sage said.
"This is a major milestone because Rakitū is the last DOC administered island in the Hauraki Gulf Marine Park to be made pest-free," Sage said.
"Rakitū represents another step towards a Predator Free Aotearoa New Zealand."
There are now more than 40 pest-free islands in the region, which provide safe havens for endangered native wildlife including takahē, kakapo, kōkako, kiwi, geckos, skinks, bats, wētāpunga and tuatara.
Sage said Rakitū was farmed for more than a century and a restoration programme would now be developed.
Ngāti Rehua Ngātiwai ki Aotea and DOC rid Rakitū of rats in 2018.
The island sits on a native seabird highway that spans a chain of pest-free islands from the Poor Knights, north of Whangarei, to the Mercury Islands, south of Aotea/Great Barrier Island.