Westfalenbank AG was founded by several industrial companies of the Ruhr region (Bergbau-AG Lothringen, Essener Steinkohlenbergwerke AG and Maschinenfabrik Henschel & Sohn AG).

The bank experienced a boom in the 1950s, when various business groups in the Ruhr region used it as their principal bank. When the chemical group BASF took over Wintershall AG in 1969, the bank shares were sold to Bayerische Hypotheken- and Wechselbank AG, which in turn merged with HypoVereinsbank at a later point in time. In 2002 the Westfalenbank was sold to Düsseldorf-based Falke-Bank AG. In 2004 HypoVereinsbank bought back the Westfalenbank.

In the subsequent years, HypoVereinsbank filleted individual sections of the Westfalenbank: asset management was bought by financial services company Fortis, retail banking went to Merck Finck & Co, corporate banking with an asset portfolio of around one billion Euros remained with HypoVereinsbank. Everything else was sold to the American Crown Group as distressed securities. In summer 2012 the Koidl Group acquired the Westfalenbank trademark rights from the Bochum bank company in liquidation.