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 from the 2010 census count of 540, which in turn reflected an increase of 18 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.