Blawenburg is an unincorporated community and census-designated place (CDP)[11] located within Montgomery Township, in Somerset County, in the U.S. state of New Jersey.

The area that was eventually known as Blawenburg was settled by John Blaw prior to 1742 when he purchased 400 acres (160 ha) of farmland from Abraham Van Horn, a merchant of New York City and a large New Jersey landholder, and 95 acres (38 ha) adjacent to this tract from Nicholas Lake of New Brunswick.

[1][2] The 2010 United States census counted 280 people, 107 households, and 73 families in the CDP.

It was added to the National Register of Historic Places on December 7, 1990, for its significance in agriculture, architecture, religion and exploration/settlement.

[16] The Reformed Dutch Church of Blawenburg was added individually to the NRHP in 1985 and contributes to the district.

The William Sherman House, built c. 1856, features Greek Revival and Italianate style.