What is now Rochelle Park was incorporated as Midland Township on March 7, 1871, from portions of New Barbadoes Township. Rochelle Park was formed as a township by an Act of the New Jersey Legislature on November 5, 1929, replacing Midland Township, based on the results of a referendum held on that same day that passed by a 503-69 margin. The main impetus behind the change in name was to avoid confusion with the nearby community of Midland Park.
As of the census of 2000, there were 5,528 people, 2,061 households, and 1,393 families residing in the township. The population density was 5,287.7 people per square mile (2,032.7/km). There were 2,111 housing units at an average density of 2,019.2/sq mi (776.2/km). The racial makeup of the township was 90.09% White, 0.45% African American, 0.04% Native American, 6.02% Asian, 2.03% from other races, and 1.37% from two or more races. Hispanic or Latino of any race were 8.57% of the population.
There were 2,061 households out of which 26.0% had children under the age of 18 living with them, 55.7% were married couples living together, 9.1% had a female householder with no husband present, and 32.4% were non-families. 27.3% of all households were made up of individuals and 16.6% had someone living alone who was 65 years of age or older. The average household size was 2.52 and the average family size was 3.12.
In the township the population was spread out with 18.7% under the age of 18, 5.9% from 18 to 24, 27.9% from 25 to 44, 23.7% from 45 to 64, and 23.9% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 84.1 males. For every 100 females age 18 and over, there were 79.2 males.
The median income for a household in the township was $60,818, and the median income for a family was $74,016. Males had a median income of $43,580 versus $36,827 for females. The per capita income for the township was $25,054. About 0.4% of families and 2.9% of the population were below the poverty line, including 2.2% of those under age 18 and 6.0% of those age 65 or over.
New Jersey Transit bus routes 144, 145, 148, 162, 163, 164, 175, 709, 712, 758, and 770 serves Rochelle Park.
Route 17 and the Garden State Parkway travels through Rochelle Park.