梅莱特县（Mellette County, South Dakota）是美国南达科他州中南部的一县。面积3,392平方公里。根据美国2000年人口普查，共有人口2,083人。县治怀特里弗（White River）。

成立于1909年3月9日，县政府成立于1911年5月25日。县名纪念达科他准州最后一任州长、南达科他州首任州长亚瑟·C·梅莱特（Gideon Curtis Moody）。

Mellette County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 2,048. Its county seat is White River. The county was created in 1909 and organized in 1911. It was named by European-American settlers after Arthur C. Mellette, the last Governor of the Dakota Territory and the first Governor of the state of South Dakota.