After graduating as a merchant in wholesale and foreign trade, Klein took over his parents' beveragewholesaleKlein Getränke GmbH in Saarbrücken and founded the alldrink Getränkefachmarktkette (alldrink chain of warehouse stores for beverages).[2] Due to changes in trade, he established a system-controlled logistics center for beverages in Neunkirchen/Saar in 1995.[3] In 1998, first HM InterDrink Getränke Service GmbH and subsequently Winkels Getränke Holding took over the majority of Klein Getränke GmbH,[4] which merged with Gross Getränkevertrieb GmbH in 2001.[5]
At the end of 2002 he relocated to Switzerland and founded ProCon Invest AG (real estate and investments).[6] In 2014 Klein bought the business premises of C&A in Ulm.[7] In 2019 the foundation of ProCon Real Estate GbR, a family office, took place.[8] The family office acquired in 2019 a premium property in the city center of Freiburg im Breisgau.[8] Klein's real estate investments became known through transactions in inner-city prime locations.[9]
Werner Klein has two children, son Marc Klein and daughter Linda Klein, has been married since May 2024 and lives with his wife Christine in Lucerne on Lake Lucerne.[12] Klein has had Swiss citizenship in addition to German citizenship since 2016.
^"Service wird ganz großgeschrieben" (in German). Saarbrücker Zeitung. April 11, 1998.
^""Impulsgeber" im alten Erzlager: Logistik-Center der Firma Klein Getränke im Bau" (in German). Saarbrücker Zeitung. August 18, 1994.
^"Fusion mit HMI" (in German). Rhein-Zeitung. December 23, 1998.
^"Für sichere Zukunft gerüstet: Klein Getränke in Neunkirchen geht mit Biergroßvertrieb in Dillingen zusammen" (in German). Saarbrücker Zeitung. January 26, 2001.