Geithner served as a Treasury Department official during the Clinton administration, where he played a major role in negotiating assistance packages for South Korea and Brazil.
Summers, 53, a former treasury secretary under Bill Clinton and one-time president of Harvard University, will advise Obama from the White House. Officials said he would coordinate the federal response to the economic meltdown across several agencies, including a plan Obama announced Saturday to create or save 2.5 million jobs by rebuilding infrastructure and modernizing schools while developing alternative energy sources and more efficient cars.
During the Clinton administration, Summers helped craft the U.S. support program for Mexico during its 1995 financial crisis. He later helped lead the U.S. response to the Asian financial crisis of 1997.
Geithner and Summers were scheduled to appear with Obama at a press conference in Chicago Monday morning.
The announcement comes as Obama moves quickly to fill slots for his incoming administration. On Saturday, he named longtime spokesman Robert Gibbs as White House press secretary.
Ellen Moran will be director of communications in charge of getting Obama's message out. Her deputy in the White House will be Dan Pfeiffer, the communications director for Obama's presidential transition team.
In other positions, Obama is virtually certain to offer Congressional Budget Office chief Peter Orszag the job of directing the White House Office of Budget and Management, and Orszag is likely to accept, Democratic officials said Saturday.
New York Sen. Hillary Rodham Clinton also is in line to become secretary of state, while Obama's choice for attorney general is Eric Holder. He held the No. 2 slot in the Justice Department in President Bill Clinton's administration.