Knox City is located on high ground 3.5 mi (5.6 km) from the upper Brazos River.

According to the United States Census Bureau, Knox City has a total area of 0.85 square miles (2.2 km2), all land.

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

[6] As of the 2020 United States census, 1,065 people, 427 households, and 259 families resided in the town.

The town is served by the Knox City-O'Brien Consolidated Independent School District.

Knox City and Lyndon Baty were featured in a 2014 episode of Snap Judgment on artificial intelligence.