Harry Patterson was hit by an empty car rolling down a steep driveway at his home in Alltwen in the Swansea Valley almost two years ago.
After his death, his parents set up Harry's Fund and successfully applied to local not-for-profit organisation WREN (Waste Recycling Environmental Limited) for £75,000 to build a park on land donated by Cilybebyll Community Council.
Harry's mother, Michelle, said: "This grant means we can achieve our first goal in building a park, which will bring a community together and help us remember Harry for all our days."
The park, due to open next month, has been designed by Groundwork and Wicksteed Playscapes and landscaped by Port Talbot's Afan Landscapes.
Singers The Tenors of Rock and actor Craig Gallivan have become fund patrons.