Although its roots date back more than a century Sydbank was first established in 1970 through a merger of four local banks in Southern Jutland. In the 1980s the Bank began expanding its domestic branch network outside Southern Jutland.
Between 1980 and 1989 Sydbank established a branch in Copenhagen (1981); merged with Århus Bank (1983) and Fynske Bank (1984); and partially acquired two Copenhagen-based banks, 6. juli Banken (1987), and Fællesbanken (1988). Outside Denmark, Sydbank established branches in Germany in 1984, 1985 and 2007.
In 1990 Sydbank merged with Sparekassen Sønderjylland, the largest savings bank in Southern Jutland, which gave the merged entity the leading market position in that area.
In 1994 Sydbank acquired the sound, basic banking activities of Varde Bank (which was then in financial difficulties) and, it acquired the basic banking activities of Aktivbanken from its insurance company parent, Topdanmark. Purchasing the core businesses of Varde Bank and Aktivbanken doubled Sydbank's business volume as well as the number of staff.
In 2000 Sydbank obtained its first rating from Moody's.
In the years following the turn of the millennium Sydbank grew and is now nationwide. In 2002 Sydbank acquired Egnsbank Fyn and in the ensuing years it set up a number of branches in central Jutland and North Zealand. In 2002 Sydbank established a subsidiary bank, Sydbank (Schweiz) AG, however in 2011 the activities were transferred to Sydbank in Germany – now home to the Bank’s foreign private banking operations. In 2008 Sydbank acquired bankTrelleborg.
In 2012 Sydbank acquired branches and clients from Tønder Bank, and in December 2013 Sydbank acquired DiBa Bank.