The town was originally named Glendale as it was between Glen Ellyn and Bloomingdale, but after a conflict arose with the small town of Glendale in Southern Illinois, the city decided in March 1960 to add the term Heights, in reference to its different topographies, thus becoming Glendale Heights.
According to the United States Census Bureau, the village has a total area of 5.4 square miles (14.0 km²), all of it land.
There were 10,791 households out of which 38.2% had children under the age of 18 living with them, 55.5% were married couples living together, 9.9% had a female householder with no husband present, and 29.6% were non-families. 22.8% of all households were made up of individuals and 3.1% had someone living alone who was 65 years of age or older. The average household size was 2.94 and the average family size was 3.54.
In the village the population was spread out with 26.9% under the age of 18, 11.5% from 18 to 24, 36.8% from 25 to 44, 19.9% from 45 to 64, and 5.0% who were 65 years of age or older. The median age was 30 years. For every 100 females there were 104.2 males. For every 100 females age 18 and over, there were 102.1 males.
The median income for a household in the village was $56,285, and the median income for a family was $64,115. Males had a median income of $40,830 versus $30,132 for females. The per capita income for the village was $21,911. About 4.7% of families and 6.1% of the population were below the poverty line, including 8.6% of those under age 18 and 7.8% of those age 65 or over.