Donald J. Trump State Park is a 436-acre (1.8 km²) state park in the towns of Yorktown and Putnam Valley in Westchester and Putnam counties, New York.

The park consists of property that was donated to New York State in 2006 by the real estate developer Donald Trump. Maintenance of the park was halted in 2010 due to budget constraints, and the park remains largely undeveloped. Most of the buildings have been demolished; only a few foundations and the existing tennis court remain. Since 2015, there have been several calls to rename the park.

Trump purchased the property in 1998 with plans to build a $10 million private golf course. Totalling $2.5 million, it was purchased in two sections: Indian Hill for $1.75 million and French Hill for $750,000. The land contained significant wetlands, and development faced strict environmental restrictions and permitting requirements. He donated it in 2006 after he was unable to gain town approvals to develop the property. At that time, Trump claimed the parcel was worth $100 million. He used the donation as a tax write-off. In the press release announcing the donation, Governor George Pataki praised the gift, and Trump said, "I have always loved the City and State of New York and this is my way of trying to give something back. I hope that these 436 acres of property will turn into one of the most beautiful parks anywhere in the world."

New York State announced the park's closure due to budget cuts in February 2010. It was questioned whether the closure was necessary since the operating budget for the park was only $2,500 a year and it was maintained by workers from the nearby Franklin D. Roosevelt State Park. Although Trump threatened to somehow revoke his donation after the closure was announced, the land remains owned by the state of New York and controlled by its Office of Parks, Recreation and Historic Preservation.

An attempt to convert a portion of the park's French Hill section for use as a dog park in 2010 revealed that at least one of the park's abandoned buildings contained asbestos. By 2012, the planned dog park remained on hold due to difficulties raising funds for fences and asbestos abatement.

The park is not listed at the New York State Office of Parks, Recreation and Historic Preservation park locator, although signs along the nearby Taconic State Parkway direct visitors to Donald J. Trump State Park. During a 2015 visit by The Rachel Maddow Show, there were no signs of any recent upkeep; instead, the publicly accessible land was found to contain crumbling graffiti-covered buildings, empty map kiosks, and weed-choked parking lots.

In 2017, an article on website The A.V. Club framed the park as an "abandoned wasteland", with "muddy fields, overgrown tennis courts, and dilapidated buildings" and a swimming pool in disrepair.

Park access improvements including an asphalt driveway, gravel parking lot, entrance gates, wood fencing, and native tree and shrub plantings were noticed in 2020.