According to the U.S. Census Bureau, the census area has a total area of 45,504 square miles (117,850 km2), of which 40,570 square miles (105,100 km2) is land and 4,934 square miles (12,780 km2) (10.8%) is water. Its territory includes the large offshore Nunivak Island in the Bering Sea.
There were 4,226 households out of which 51.00% had children under the age of 18 living with them, 50.20% were married couples living together, 15.20% had a female householder with no husband present, and 24.90% were non-families. 19.90% of all households were made up of individuals and 2.80% had someone living alone who was 65 years of age or older. The average household size was 3.73 and the average family size was 4.41.
In the census area the population was spread out with 39.80% under the age of 18, 9.70% from 18 to 24, 28.90% from 25 to 44, 16.40% from 45 to 64, and 5.20% who were 65 years of age or older. The median age was 25 years. For every 100 females there were 113.20 males. For every 100 females age 18 and over, there were 112.80 males.
Bethel Census Area is one of only 38 county-level census divisions of the United States where the most spoken language is not English and one of only 3 where it is neither English nor Spanish. 63.14% of the population speak a Yupik language at home, followed by English at 34.71%.