According to the United States Census Bureau, the town has a total area of 2.9 square miles (7.4 km2), of which, 2.9 square miles (7.4 km2)is land and 0.35% is water.
Kilmarnock hosts the Holly Ball, a debutante ball founded in 1895, at the Indian Creek Yacht and Country Club every December.
As of the 2020 census,[5] the total population is 1,445. The town has 802 total housing units, with 687 occupied and 645 of those belonging to families. 115 houses were vacant. 54.7% of homes were owned instead of rented. Of the population, 926 are white, 446 are black, 37 are mixed race, 18 are Hispanic or Latino, 17 are Asian, 3 are American Indian, 1 is Hawaiian, and 15 are some other race.
The median age in Kilmarnock is 60.2. 42% of the population is 65 years or older. 10.7% of the population is a veteran, with 89% of those being male. 23.1% of the population had a bachelor's degree or other form of higher education.
Outskirts of Kilmarnock
The median household income was $36,875. 29.4% of the population was below the poverty line, 77.4% of which were under 18. 23.9% of the remainder was between 18 and 64 while the remaining 17.4% was 65 or older. The median income for families is $44,242 while for married-couple families it is $71,125 and $25,677 for non-family households.