Millbrook is a village in Dutchess County, New York, United States. Millbrook is located in the Hudson Valley, on the east side of the Hudson River, north of New York City. Millbrook is near the center of the Town of Washington. As of the 2010 Census, Millbrook's population was 1,452. It is often referred to as a low-key version of the Hamptons and is one of the most affluent villages in New York.