Vizeum will run the UK business, which is worth £10 million this year.
Dentsu Aegis will oversee media in Germany, Sweden, Austria and Hungary.
WPP’s MediaCom previously held the account. The shop beat the incumbent, Initiative, in a pitch in 2008.
E.ON consolidated its UK advertising and CRM activity into Engine last year after a review run by ISBA. The business is led by Partners Andrews Aldridge.
MullenLowe London was the incumbent on the creative account and did not repitch. Havas Helia previously handled direct marketing.
E.ON was formed in 2000 by the merger of Veba and Viag, two of Germany’s biggest industrial groups.
Vizeum confirmed the appointment but declined to comment further.
A spokesman for E.ON said: "We can confirm that we have successfully completed our tender for an international media agency. Dentsu Aegis will be this media agency, working for E.ON in the UK, Sweden, Germany, Hungary and Austria in the future."