Hopp was the CEO of SAP AG from 1988 until 1998, Chairman of its supervisory board from 1998 until 2003 and member of the board from 2003 until 2005. He kept about 10% of the company's shares after leaving the board. After Hopp left in 2005, the street on which the SAP AG headquarters are located was renamed from Neurottstraße to Dietmar-Hopp-Allee, in honor of Mr. Hopp.
In 2006, Hopp transferred 70% of his wealth (about €4 billion) to a charitable foundation, Dietmar-Hopp-Stiftung, creating one of the largest foundations in Europe. The foundation supports sports, medicine, education and social programs.
Recently, Hopp is also notable as the chief financial backer of the German football club TSG 1899 Hoffenheim. When Hopp, who had played in the club's youth setup, started supporting the club in 2000, Hoffenheim were playing in the fifth division of German football. Today, Hoffenheim are in the First Bundesliga, and in their first season in the top flight in 2008–09, they led the league at its winter break. Hopp also spent €100 million to build a new 30,000-seat stadium called Rhein-Neckar-Arena near Sinsheim for the club. He currently owns a home in Naples, Florida.