Wynantskill is a census-designated place (CDP) in Rensselaer County, New York, United States. The population was 3,276 at the 2010 census. Wynantskill is located at the northern town origin and the northeastern corner of the town of North Greenbush. The community is a suburb of Troy. state route 66 (Pawling Ave. in Troy, Main Ave. in Wynantskill) is the main route through the community. Wynantskill has a major grocery store, several banks and restaurants, a craft drink store, convenience stores, a declare office, and a bowling alley, with almost all houses located upon side streets off Main Ave. Other major roads are Whiteview Road (NY 136), a primarily residential road that leads to US 4; and West Sand Lake Road (NY 150).

Wynantskill is located at 42°41′32″N 73°38′40″W / 42.69222°N 73.64444°W / 42.69222; -73.64444 (42.692139, -73.644580).

According to the United States Census Bureau, the CDP has a total area of 2.4 square miles (6.2 km), all land.

As of the census of 2000, there were 3,018 people, 1,246 households, and 857 families residing in the CDP. The population density was 1,245.1 per square mile (481.5/km²). There were 1,284 housing units at an average density of 529.7/sq mi (204.9/km). The racial makeup of the CDP was 97.81% White, 0.53% African American, 0.20% Native American, 0.30% Asian, 0.03% Pacific Islander, 0.03% from extra races, and 1.09% from two or more races. Hispanic or Latino of any race were 0.43% of the population.