Fieldsboro is a borough in Burlington County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 526, a decrease of 14 (−2.6%) from the 2010 census count of 540, which in turn reflected an increase of 18 (+3.4%) from the 522 counted in the 2000 census. The borough, and all of Burlington County, is a part of the Philadelphia-Reading-Camden combined statistical area and the Delaware Valley.