The company has committed to an investment of ZAR20bn ($2bn) to expand the Venetia operations until 2042.
Once the new mine begins production in 2021, the underground mine will become the largest diamond operation in South Africa.
De Beers Group CEO Philippe Mellier noted that this investment allows the company to assure long-term supply for its Sightholders, mainly those with operations in South Africa.
"Our Sightholders have significant investments in the local cutting industry and this new underground mine will provide a large and predictable supply of rough diamonds for decades to come," Mellier added.
Construction at the mine is estimated to take nine years; De Beers will employ domestic workers and source a majority of the equipment and services in South Africa, the company said.
Open pit mining operations will continue as development progresses. The new mine is expected to produce 96 million carats during the life of the mine.
DBCM CEO Phillip Barton stated, "Venetia will play a major role in the future of De Beers and we have therefore been preparing for years to meet tight deadlines and high standards so that Venetia Underground is ready to begin producing South African diamonds by 2021."
