Kahurangi National Park in northwest Nelson is now almost 900 hectares larger.
Conservation Minister Maggie Barry announced today an additional five parcels of land have been gazetted, meaning the park now covers 453,791 hectares.
The new national park land includes an area in the Cobb Valley and land west of Mt Burnett that had been surrounded by the park.
"The 49 hectares of Cobb Valley land is particularly significant as it contains several rocky magnesite outcrops which are a hotspot for native plants - nine of which are found nowhere else on Earth," said Ms Barry.
The government said yesterday the largest 1080 pest control operation in New Zealand's history is to start in Kahurangi next week.
The $21 million Battle of the Birds programme will cover about 10 percent of the country's conservation estate.
RNZ reported last year that a parcel of the land earmarked for inclusion in Kahurangi was formerly the subject of a mining application from a company wanting access to quarry soapstone.