Mjällby is a locality situated in Sölvesborg Municipality, Blekinge County, Sweden with 1,254 inhabitants in 2010. It is located on the Listerlandet peninsula. The town has traditionally lived of fishing. The nearby harbour of Nogersund is the third largest fishery harbour in Sweden. The fishery industry is also dominant on the peninsula. Listerlandet is also the fur farming centre of Sweden. Fur farming is currently under heavy political debate in Sweden. The mathematician Lars Hörmander was born in Mjällby.