According to the United States Census Bureau, the town has a total area of 0.8 square miles (2.1 km2), all land.

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

[3] As of the 2020 United States census, there were 1,273 people, 584 households, and 301 families residing in the town.

The Mississippi Department of Corrections (MDOC) operates the Quitman County Community Work Center (CWC) in an area near Lambert.

Camp B, an inmate housing unit, was a satellite complex located away from the main Parchman prison property in unincorporated Quitman County,[8] near Lambert.

The Town of Lambert is served by the Quitman County School District.