In the future, customers in Germany and other EU countries will have to pay in rubles for gas deliveries from Russia.
Russian President Vladimir Putin on Wednesday instructed the government to stop accepting payments in dollars or euros.
Deliveries would continue to be fully guaranteed, the Kremlin chief assured in a government video conference that was broadcast on state television.
Payment for Russian goods in foreign currency has lost its meaning.
The "unfriendly states" blacklisted by Russia are affected.
This includes Germany and all other EU countries, but also the USA, Canada and Great Britain.
The announcement promptly strengthened the Russian currency, which is under massive pressure.
The central bank and the Russian government now have a week to determine the modalities for switching from foreign exchange payments to ruble payments, Putin said.
The West itself has devalued its currencies by freezing Russian assets abroad.
As a reaction to the sanctions imposed by the West, the Russian government had already decided at the beginning of the month that its own financial obligations to "unfriendly states" would only be settled in rubles.
These include Ukraine, Switzerland and Japan.