Dartford Borough Council has signed a £4m deal to buy 23 acres of parkland from the drug firm GlaxoSmithKline.
The deal will almost double the size of Dartford's Central Park
It is part of the controversial regeneration of the town which includes building a road through Central Park.
The purchase of Acacia House follows nearly nine months of discussion and will nearly double the park's size.
Plans for the park scheme, which also includes 500 flats and a supermarket, were opposed by many residents before being approved last August.
A protest petition signed by 13,000 people was delivered to Dartford Borough Council and objectors staged a number of marches.
The new land is on the other side of the River Darent, which will run through the centre of the enlarged space with bridges linking its banks.
The council says it plans to restore the park to its original splendour, in grand Edwardian style.
It promises additional facilities including sports, social and recreational areas to encourage greater use of the park.