"Gazprom has always been a reliable partner of VNG and Germany, and I want to assure you that it will be so in the future," Alexei Miller said at an event to mark the 50th anniversary of Germany's largest gas distribution company, VNG.
German Chancellor Angela Merkel was expected to address the celebration, which gathered guests from Germany and its partners, including Russia, France, Norway and Britain.
Miller said safe and reliable energy supplies had always been central to Gazprom.
"Energy security is a bilateral thing. This means there should be both a reliable supplier and a reliable consumer," the businessman said, referring to Germany, Russia's largest gas importer.
Gazprom and VNG first started working together 35 years ago.
Despite the close ties in the energy sphere, there have been tensions of late between Moscow and Berlin over Russia's decision to recognize the independence of Abkhazia and South Ossetia, with Merkel describing the move as "totally unacceptable."
