Both Yellen and Bernanke are scheduled to appear with Obama at the White House on Wednesday for a formal announcement.
Bernanke's term ends in January, completing a remarkable eight-year tenure in which he helped pull the U.S. economy out of the worst financial crisis and recession since the 1930's.
Under Bernanke's leadership, the Fed created extraordinary programs after the financial crisis erupted in 2008. It lent money to banks after credit markets froze, cut its key short-term interest rate to near zero and bought trillions in bonds to lower long-term borrowing rates.
Those programs are credited with helping save the U.S. banking system.
Yellen emerged as the leading candidate after Lawrence Summers, a former Treasury secretary whom Obama was thought to favour, withdrew from consideration last month in the face of rising opposition.
Yellen, 67, would likely continue steering Fed policy in the same direction as Bernanke. A close ally of the chairman, she has been a key architect of the Fed's efforts under Bernanke to keep interest rates near record lows to support the economy.
As vice chair since 2010, Yellen has helped manage both the Fed's traditional tool of short-term rates and the unconventional programs it launched to help sustain the economy after the financial crisis erupted in 2008. These include the Fed's monthly bond purchases and its guidance to investors about the likely direction of rates.
"She's an excellent choice and I believe she'll be confirmed by a wide margin," said Sen. Chuck Schumer, D-N.Y., a member of the Senate Banking, Housing and Urban Affairs Committee.
Obama's choice of Yellen coincides with a key turning point for the Fed. Within the next several months, the Fed is expected to start slowing the pace of its Treasury and mortgage bond purchases if the economy strengthens. The Fed's purchases have been intended to keep loan rates low to encourage borrowing and spending.
Yet even after the Fed scales back its bond buying, its policies will remain geared toward keeping borrowing rates low to try to accelerate growth and lower unemployment. The unemployment rate is a still-high 7.3 per cent. Few expect the Fed to start raising the short-term rate it controls before 2015 at the earliest.
Yellen had long been considered a logical candidate for the chairmanship in part because of her expertise as an economist, her years as a top bank regulator and her experience in helping manage the Fed's polices. Her understanding of the financial system is widely respected: Before the crisis struck, she was among a minority of top economists who had warned correctly that subprime mortgages posed a severe threat.
On the Fed, Yellen has built a reputation as a "dove" — someone who is typically more concerned about keeping interest rates low to reduce unemployment than about raising them to avert high inflation. Her nomination could face resistance from congressional critics who argue that the Fed's low-rate policies have raised the risk of high inflation and might be breeding dangerous bubbles in assets like stocks or real estate.
Still, Yellen has said that when the economy finally begins growing faster and rates will need to be raised to prevent high inflation, she will move in that direction.
In the weeks leading to her selection, Yellen and Summers emerged as the two top contenders and were drawn into a highly unusual public battle. Yellen and Summers themselves kept quiet. But their warring camps waged a fight that stirred up Congress, spawned opinion columns and letters from Congress and triggered commentary from notables both inside and outside the economics profession.
Yellen drew outspoken support from Senate Democrats, a third of whom signed a letter this summer urging Obama to choose her. Last month, more than 350 economists signed a letter to Obama urging him to nominate Yellen. The letter argued that Yellen understands the relationship between interest-rate policy and economic growth, possesses a "nuanced understanding" of job markets and is inclined as a policymaker to consider all points of view.
If confirmed by the Senate, Yellen would be the first Democrat chosen to lead the Fed since Paul Volcker was picked by Jimmy Carter in 1979. Bernanke, who served for eight years, and his predecessor, Alan Greenspan, who did so for 18 1/2 years, were Republicans. She would also be the first vice chair of the Fed to ascend to the chairmanship.
Yellen served as a Fed board member for three years in the 1990s before leaving to head the Council of Economic Advisers in the Clinton administration. She also served for six years as president of the Fed's regional bank in San Francisco before Obama chose her in 2010 for the No. 2 spot on the Fed's seven-member board in Washington.
In addition to helping devise the Fed's rate policies, she has been instrumental in carrying out another top priority of Bernanke's — making the Fed, an institution whose operations were long walled off from the public view, far more open and transparent. The Bernanke-led Fed did so through news conferences, clearer public communications and detailed guidance about the Fed's expectations for the economy and policymaking.
Yellen, like Bernanke, was a distinguished college economics professor before joining the Fed. She taught at the University of California at Berkeley from 1980 until 1994 when President Bill Clinton chose her to join the Fed's board in Washington. She served on the Fed's board of governors until February 1997, when Clinton chose her to lead the White House Council of Economic Advisers.
Yellen would not only be the first woman to head the U.S. central bank; she also would be the first woman ever to head a major central bank anywhere in the world.
Yellen was born in Brooklyn and graduated from Brown University in 1967 with highest honours in economics. She received her doctorate in economics in 1971 from Yale, where she studied under the Nobel Prize-winning economist James Tobin. In a 1997 interview with Business Week magazine, Tobin described Yellen as having "a genius for expressing complicated arguments simply and clearly."
She was an assistant professor at Harvard University from 1971 to 1976 and then worked as an economist at the Federal Reserve in Washington from 1977 to 1978. She met her husband, George Akerlof, in a Fed cafeteria. The two worked together for many years on the Berkeley faculty. Akerlof shared a Nobel in economics in 2001 with Joseph E. Stiglitz and A. Michael Spence.
Yellen was known as a pragmatist in her economic research, which ranged from studies on urban gang behaviour to currency problems facing Germany after its reunification.