Mjällby Allmänna Idrottsförening, also known simply as Mjällby AIF, Mjällby or MAIF, is a Swedish professional football club based in Hällevik in Sölvesborg Municipality. The club is affiliated to Blekinge Fotbollförbund and play its home games at Strandvallen. The club colours, reflected in their crest and kit, are yellow and black. Formed on 1 April 1939, the club have played eight seasons in Sweden's highest football league Allsvenskan, the club's first season in the league was in 1980. The club are currently playing in Allsvenskan. With nine seasons in the top division Allsvenskan, Mjällby AIF is the most successful football team from the province of Blekinge.

Allsvenskan is a Swedish professional league for men's association football clubs. It was founded in 1924 and is the top tier of the Swedish football league system, operating on a system of promotion and relegation with Superettan. Seasons run from late March or early April to the beginning of November, with the 16 clubs all meeting each other twice, resulting in a 30-match season, for a total of 240 matches league-wide.