It follows the European Commission and the Russian Antimonopoly Authority’s approval of the takeover by Fortum.
E.ON received €3.8 billion (£3.3bn) for its remaining shares in Uniper.
Johannes Teyssen, Chief Executive of E.ON said: “The sale of our remaining shares in Uniper to Fortum marks the end of a chapter in E.ON’s history.
“At the same time, E.ON is already writing a new, groundbreaking chapter for the future. We will become the leading provider of intelligent energy networks and modern customer solutions in Europe.”