| Official Name: | Mjällby |
| Pushpin Map: | Sweden Blekinge#Sweden |
| Subdivision Type: | Country |
| Subdivision Name: | Sweden |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Sölvesborg Municipality |
| Subdivision Type2: | County |
| Subdivision Name2: | Blekinge County |
| Subdivision Type1: | Province |
| Subdivision Name1: | Blekinge |
| Area Footnotes: | [1] |
| Area Total Km2: | 1.67 |
| Population As Of: | 31 December 2010 |
| Population Total: | 1,254 |
| Population Density Km2: | 753 |
| Timezone: | CET |
| Utc Offset: | +1 |
| Timezone Dst: | CEST |
| Utc Offset Dst: | +2 |
| Coordinates: | 56.05°N 55°W |
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.
Mjällby is known for its football team which has played in the Swedish national football league a few times. Among footballfans in Sweden the team of Mjällby AIF is known as "the team that always returns". In September 2009 the team once again qualified for the highest division and played five seasons in Allsvenskan before being relegated at the end of the 2014 season.
The mathematician Lars Hörmander was born in Mjällby.
A suburb of the town built by a local housing company was unofficially known for around 40 years by locals as Negerby (Negro village) because of the black chimneys on the houses. In 2012 the use of this name was reported by a journalist and following the public outcry the housing company decided to use the temporary name of Slottsstaden (Castle City).[2]