The 41-year-old economist, who is widely loathed by the Communists and nationalists because he masterminded Russia's privatisation campaign, was made first deputy to the Prime Minister, Viktor Chernomyrdin.
The move, which was met by a chorus of complaints by opposition leaders, is part of the much-anticipated shake-up of government by Mr Yeltsin as he seeks to show that he is back at the helm after eight months of absence through sickness.
It suggests the president's return is genuine, at least for now. During Yeltsin's illness, Mr Chubais came to be seen as the most influential official in the country, controlling access to the presidential chamber and shaping policy by working with the president's daughter, Tatyana, and a coterie of Moscow businessmen. Now he is keen for a new and powerful role.
Last night, it appeared his wish was fulfilled. He was being tipped to take charge of Russia's economy, which remains in the doldrums, defying predictions that it would begin to grow. This move will be welcomed by interests in the West, notably the International Monetary Fund which has been trying to make Russia stick to the stringent terms of a $10bn (pounds 6bn) loan.