North Great River is a hamlet and census-designated place (CDP) in the Town of Islip, in Suffolk County, on Long Island, in New York, United States.

[2] The hamlet is served by the Islip Terrace Post Office (11752).

There were 1,167 housing units at an average density of 510.8 per square mile (197.2/km2).

10.6% of all households were made up of individuals, and 4.3% had someone living alone who was 65 years of age or older.

North Great River is located primarily within the East Islip Union Free School District, although a small portion of the northwestern corner of the hamlet is within the Central Islip Union Free School District.