Remsen was named for Henry Remsen II, the original proprietor of the township and the inheritor of the Remsenburgh patent, which embraced some in Oneida and Herkimer counties and was granted in 1766 to Remsen and four other New York merchants. Remsen, a New York City merchant and owner of Henry Remsen Jr. & Co., was the descendant of some of the earliest Dutch settlers of New Amsterdam. The town was first settled around 1792, when Barnabas Mitchell of Meriden, Connecticut settled in the area and began clearing a farm which was subsequently owned by his son Milo, and became known as the 'Milo Mitchell place.' Soon afterwards, Mitchell was joined by Nathaniel Rockwood, John Bonner, Perez Farr, Bettis Le Clerc, Jonah Dayton, John Kent and Shubael Cross, all of whom came from New England to settle in Remsen. In September 1795, five families from Wales settled in the vicinity, marking the beginning of a substantial Welsh presence in the area. The Town of Remsen was formed in 1798 from part of the Town of Norway in Herkimer County, New York when Oneida County was formed. In 1869, part of Remsen was used to form the new Town of Forestport.
As of the census of 2000, there were 1,958 people, 745 households, and 517 families residing in the town. The population density was. There were 991 housing units at an average density of. The racial makeup of the town was 98.26% White, 0.36% Black or African American, 0.15% Native American, 0.41% Asian, and 0.82% from two or more races. Hispanic or Latino of any race were 0.15% of the population. There were 745 households out of which 36.2% had children under the age of 18 living with them, 54.1% were married couples living together, 11.5% had a female householder with no husband present, and 30.5% were non-families. 22.6% of all households were made up of individuals and 9.1% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.12. In the town, the population was spread out with 28.1% under the age of 18, 7.3% from 18 to 24, 28.9% from 25 to 44, 24.9% from 45 to 64, and 10.9% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 99.8 males. For every 100 females age 18 and over, there were 99.2 males. The median income for a household in the town was $34,968, and the median income for a family was $41,042. Males had a median income of $30,938 versus $22,989 for females. The per capita income for the town was $16,394. About 8.5% of families and 11.2% of the population were below the poverty line, including 10.5% of those under age 18 and 10.4% of those age 65 or over.
The town and village of Remsen is served by the Remsen Central School District. Timothy Jenny serves as Superintendent of the District which includes Remsen Elementary, and Remsen Junior-Senior High. As of 2018, the student population of Remsen Elementary is 244, and Remsen Junior-Senior High is 205. The mascot of both schools is the Remsen Rams. School colors are black and orange. Remsen Junior-Senior High Athletic program competes in Class D of the New York State Public High School Athletic Association. Athletics offered are Cross Country, Soccer, Basketball, Volleyball, Cheerleading, Baseball, Softball, Track and Field.