Named for William Darne, the community was built on 2,000 acres of land inherited by his wife from her father Charles Gassway's 'Mount Pleasant' land grant. Originally, the town was referred to as Mount Pleasant, but the name shifted in popular parlance to Darne and eventually Darnestown. The community was located halfway between Montgomery Court House (modern-day Rockville) and the mouth of the Monocacy River, and originally consisted of a tavern, a pair of blacksmiths, a wheelwright, a single store, and a log building which served as both a school and the home of several churches. The community's greatest economic boom was during the Civil War, when providing for the needs of the armies camped around Washington, DC provided new income. Following the war, however, Darnestown slowly deflated and eventually ceased being a commercial center, with only a few of the original buildings left standing. The area has since been absorbed by suburban development.
Darnestown is home to the Seneca Academy, a private school for grades Kindergarten-5. It is also home to Darnestown Elementary School and Jones Lane Elementary School, part of Montgomery County Public Schools. Though Quince Orchard High School is within several miles of most of Darnestown, all residents who are in the Darnestown Elementary School District lines will attend Northwest High School in Germantown instead. Jones Lane Elementary School students do attend Quince Orchard High School. Mary of Nazareth Catholic School, Seneca Academy, and Butler Montessori School are K-8 private schools that are in Darnestown.
Darnestown has a number of local parks, including Darnestown Square Park, Muddy Branch Stream Park, Lighthouse Point Park, and the Seneca Ridge Trail and Seneca Creek Park. Darnestown is also home to three locks on the C&O Canal. The town also borders the Montgomery County Agricultural Reserve, which is made up of lots of farmland and parks that many residents of Darnestown can appreciate. There is also a community softball league for adults in the community, with teams representing the different areas of Darnestown. It is also popular for residents to tube down the Great Seneca Creek from a starting point off of Berryville Road or Darnestown Road to the Seneca Aqueduct located near Pooles' Store, off River Road. Darnestown is also home to Seneca School House, the oldest existing schoolhouse in Montgomery County. The town is also home to a historic black community, living along Berryville Road.