The expansion will protect 23ha of land surrounding The Drip, a natural gorge, from mining or tunnelling.
Environment Minister Mark Speakman met with a representative of the Mudgee District Environment Group to discuss commitments to protect The Drip, and said the extra land for Goulburn River National Park was a win.
"This is a win for the community…saving this spectacular feature for future generations to treasure and to enjoy," Mr Speakman said.
A binding agreement has been reached with Moolarben Coal to secure more land over the next two years.
The binding agreement also ensures that there is no impact on the water supply feeding The Drip’s natural feature (the gorge) and no impact to mine subsidence from mining at The Drip and surrounding lands.
Established in 1983, Goulburn River National Park is located along the Goulburn River and surrounded by over 70,000ha of rural parcels and forest. It is a popular destination for swimming, fishing, hiking and camping.