Teyssen, 61, has led E.ON as CEO since 2010, steering the group through a tumultuous decade that included Germany's nuclear exit as well as two major structural makeovers that have turned it into Europe's largest power and gas grid player.
Birnbaum, long seen as a potential successor to Teyssen, takes over just after the group's latest overhaul, which saw it take over the broken up grid and retail assets of former rival Innogy.
"The Supervisory Board is convinced that Leonhard Birnbaum is the right person for this task," Chairman Karl-Ludwig Kley said in a statement. "He has played a key role in shaping the transformation of the energy industry over the past 20 years in various top positions and is regarded as a bridge-builder."
Birnbaum, 53, joined E.ON's board in 2013 from rival RWE, where he had held management positions since 2008. At E.ON, he was in charge of managing the integration of Innogy, which was completed this year.
Teyssen, whose track record also include ill-fated investments in Brazil as well as the spin-off of former power plant unit Uniper, already said two years ago https://de.reuters.com/article/uk-e-on-ceo/e-on-ceo-wont-renew-contract-beyond-2021-manager-magazin-idUKKBN1JH1GA that he would not renew his contract once it expires at the end of 2021.
E.ON shares have fallen nearly two thirds under his watch.
"I would like to thank Johannes Teyssen already today for leading the Group through what has probably been the most eventful phase in the company's history to date," Kley said.
The group also said it would promote senior executive Victoria Ossadnik to its management board from April 2021, where she will be responsible for digitisation.
(Editing by Michelle Adair and Mark Heinrich)
By Christoph Steitz
