Franklin Center is an unincorporated community and census-designated place (CDP) located in Franklin Township, in Somerset County, in the U.S. state of New Jersey. As of the 2020 census, Franklin Center had a population of 6,803.
According to the United States Census Bureau, Franklin Center had a total area of 6.682 square miles (17.305 km<sup>2</sup>), including 6.579 square miles (17.040 km<sup>2</sup>) of land and 0.103 square miles (0.266 km<sup>2</sup>) of water (1.53%).
Franklin Center first appeared as a census designated place in the 2010 U.S. census.
The 2010 United States census counted 4,460 people, 1,907 households, and 1,310 families in the CDP. The population density was . There were 2,141 housing units at an average density of . The racial makeup was 74.60% (3,327) White, 9.19% (410) Black or African American, 0.04% (2) Native American, 13.07% (583) Asian, 0.00% (0) Pacific Islander, 1.55% (69) from other races, and 1.55% (69) from two or more races. Hispanic or Latino of any race were 5.94% (265) of the population.
Of the 1,907 households, 13.2% had children under the age of 18; 61.7% were married couples living together; 4.8% had a female householder with no husband present and 31.3% were non-families. Of all households, 27.9% were made up of individuals and 14.7% had someone living alone who was 65 years of age or older. The average household size was 2.14 and the average family size was 2.57.
11.0% of the population were under the age of 18, 12.0% from 18 to 24, 15.5% from 25 to 44, 29.6% from 45 to 64, and 32.0% who were 65 years of age or older. The median age was 55.6 years. For every 100 females, the population had 92.0 males. For every 100 females ages 18 and older there were 91.4 males.