Gref replaces Andrei Kazmin, who will head the Russian postal service to advance its modernization.
Kazmin led the state-controlled bank from 1996, steering its development into a leading commercial bank operating on market principles.
Sberbank is now the largest bank in Eastern Europe with assets totaling over 3.5 trillion rubles ($141 billion), or more than 25% of Russia's overall banking assets.
The Sberbank supervisory board recommended Gref as the bank's new chief on October 16. Gref remained the sole candidate for the Sberbank top post.
The ex-minister's spokesperson earlier said Gref had been considering a job in the business world after President Vladimir Putin reshuffled the Cabinet more than two months ago. A company was not named, but sources close to the former minister suggested it would probably be a state-run company.
An advocate of liberal economic reforms and Russia's economics minister from 2000, Gref earlier said: "A large bank is a conservative bank. If a bank keeps more than 50% of private individuals' savings nationally, it must be highly reliable. So there must be a focus on financial stability and a proper balance of its credit portfolio in terms of risks."
Gref also said he would focus on loans to small businesses, investment and plans to develop modern services like online banking.