Waltham is a city in Mower County, Minnesota, United States.

[5] The community is in northwestern Mower County, surrounded by Waltham and independent of it.

Minnesota State Highway 56 runs along the eastern border of the city, leading north 5 miles (8 km) to Hayfield and south the same distance to Brownsdale.

Austin, the Mower county seat, is 15 miles (24 km) to the southwest via MN 56 and Interstate 90.

According to the U.S. Census Bureau, Waltham has a total area of 0.48 square miles (1.24 km2), all land.

31.3% of all households were made up of individuals, and 6% had someone living alone who was 65 years of age or older.

About 4.1% of families and 5.2% of the population were below the poverty line, including 8.3% of those under the age of eighteen and none of those 65 or over.