Mr Fischer will begin assuming his new responsibilities in early 2007, Credit Suisse said in a statement, and will report directly to the bank's CEO Oswald Grubel.
Commenting on the appointment, Mr Grubel said that Mr Fischer's strong performance record was promising for the future of the EMEA division.
"I am delighted that Lenny Fischer will join the executive board of the bank," he said.
"He did an outstanding job at Winterthur and we look forward to his continuing contribution to Credit Suisse as we grow our business across EMEA."
He added: "We see considerable growth opportunities for Credit Suisse in the region. The combined experience of Michael and Lenny will enable us to provide holistic solutions for our clients and realize the benefits of the integrated bank."