The 11.5 acres were bought for $14.6 million from the Children's Aid Society. The purchase includes woodlands with trails which will be added at the south of the park and an open grassy field to the east.
"I am pleased to announce the addition of even more parkland to the 'Borough of Parks,'" Parks Commissioner Mitchell Silver said in a statement.
"We are proud to work with President Weisberg and the Children's Aid Society to preserve this important property for generations to come."
In April of last year the city opened up the first 15-acre parcel of the park on Prospect Avenue, which was secured by an allocation of $5.6 million from former Mayor Michael Bloomberg and another $1.5 million from the City Council.
So far, the city has acquired 27-acres of the nearly 38-acre property, the Parks Department said.
The city has tried to save the land from being sold to developers since 2006 when its owners the Children's Aid Society announced it needed to sell to continue to survive.
The acquisition of the land began in 2009, and the city took control of the first section of it in 2011.
It's still trying to raise money to buy the remaining land.
Borough President James Oddo lauded the Children's Aid Society for working with the city.
"Juxtapose how they afforded government the time and opportunity to cobble resources together with others who recently sold property and you can see they are true community partners who continue to care about Staten Island," he said.
The property contains an indoor gymnasium, a stream, pond, an open field area and nine buildings planned to be used for recreational programming and management of the land, officials said.