As of the census of 2010, North Bellmore has 20,079 people, 6,555 households, and 5,407 families residing in the CDP. Thepopulation density was 7,696.6 per square mile (2,970.3/km²). There were 6,634 housing units at an average density of 2,542.9/sq mi (981.4/km²). The racial makeup of the CDP was 74.18% White, 7.2% African American, 0.06% Native American, 8.16% Asian, 0.03% Pacific Islander, 1.02% from other races, and 3.31% from two or more races. Hispanic or Latino of any race were 9.55% of the population.
There were 6,555 households out of which 39.0% had children under the age of 18 living with them, 70.1% were married couples living together, 9.2% had a female householder with no husband present, and 17.5% were non-families. 14.2% of all households were made up of individuals and 7.3% had someone living alone who was 65 years of age or older. The average household size was 3.04 and the average family size was 3.36.
In the CDP the population was spread out with 25.5% under the age of 18, 6.5% from 18 to 24, 29.8% from 25 to 44, 23.6% from 45 to 64, and 14.7% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 94.4 males. For every 100 females age 18 and over, there were 91.1 males.
The median income for a household in the CDP was $62,325, and the median income for a family was $70,067. Males had a median income of $55,384 versus $23,079 for females. The per capita income for the CDP was $27,174. About 5.4% of families and 11.0% of the population were below the poverty line, including 4.3% of those under age 18 and 4.0% of those age 65 or over.
North Bellmore is served by the North Bellmore Fire Department.