Fieldsboro is a borough in Burlington County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 540, reflecting an increase of 18 (+3.4%) from the 522 counted in the 2000 Census, which had in turn declined by 57 (-9.8%) from the 579 counted in the 1990 Census.
Fieldsboro was incorporated as a borough by an act of the New Jersey Legislature as Fieldsborough on March 7, 1850, within portions of Mansfield Township. It separated from Bordentown Township as an independent municipality c. 1894. The borough was named for the Field family, prominent early settlers in the area.
According to the United States Census Bureau, the borough had a total area of 0.36 square miles (0.93 km2), including 0.28 square miles (0.72 km2) of land and 0.08 square miles (0.21 km2) of water (22.22%).
The borough borders Bordentown Township and the Delaware River.
The 2010 United States Census counted 540 people, 206 households, and 140.904 families in the borough. The population density was 2,007.7 inhabitants per square mile (775.2/km2). There were 221 housing units at an average density of 821.7 per square mile (317.3/km2). The racial makeup was 81.11% (438) White, 12.59% (68) Black or African American, 0.00% (0) Native American, 2.04% (11) Asian, 0.00% (0) Pacific Islander, 0.37% (2) from other races, and 3.89% (21) from two or more races. Hispanic or Latino of any race were 2.78% (15) of the population.
Of the 206 households, 35.9% had children under the age of 18; 44.2% were married couples living together; 17.0% had a female householder with no husband present and 31.6% were non-families. Of all households, 23.8% were made up of individuals and 7.8% had someone living alone who was 65 years of age or older.