Knollwood is a city in Grayson County, Texas, United States.

According to the United States Census Bureau, Knollwood has a total area of 0.33 square miles (0.86 km2), all land.

[4] At the 2000 census,[3] 375 people, 143 households, and 91 families were residing in the city.

About 28.0% of all households were made up of individuals, and 3.5% had someone living alone who was 65 years of age or older.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.