Markham is a census-designated place (CDP) in Matagorda County, Texas, United States.

According to the United States Census Bureau, the CDP has a total area of 2.3 square miles (6.0 km2), all land.

Markham lies southwest, approximately 90 miles or 1+1⁄2-hour drive to downtown Houston.

There were 446 housing units at an average density of 195.0 per square mile (75.3/km2).

17.9% of all households were made up of individuals, and 7.0% had someone living alone who was 65 years of age or older.