Annandale is an unincorporated community and census-designated place (CDP)[9] located within Clinton Township, in Hunterdon County, in the U.S. state of New Jersey.

According to the United States Census Bureau, Annandale had a total area of 1.452 square miles (3.76 km2), all of which was land.

[5][12] It has a hot-summer humid continental climate (Dfa) and average monthly temperatures range from 28.2 °F in January to 72.9 °F in July.

The 2010 United States census counted 1,695 people, 658 households, and 455 families in the CDP.

[11] As of the 2000 United States census[6] there were 1,276 people, 451 households, and 354 families living in the CDP.

The district was added to the National Register of Historic Places on September 8, 1994, for its significance in architecture, commerce, and industry from 1852 to 1930.

[17] Immaculate Conception School (PreK-8) operates under the supervision of Roman Catholic Diocese of Metuchen.