Kilmarnock is a town in Lancaster and Northumberland counties in the U.S. Commonwealth of Virginia.

It is located near the mouth of the Rappahannock River and is located within the Northern Neck George Washington Birthplace American Viticultural Area winemaking appellation.

Lancaster Middle School, grades 4–8, is also located in town.

The town has 802 total housing units, with 687 occupied and 645 of those belonging to families.

23.1% of the population had a bachelor's degree or other form of higher education.