In a speech at a meeting of the joint World Bank-IMF Development Committee, Mr Geithner said the World Bank had a key role to play on food security, climate change, providing financial support for the world's poorest nations and strengthening the private sector.
Mr Geithner added that the Obama administration was committed to a policy of multilateralism and wanted to develop globally coordinated action on the economic, social and environmental problems facing the world.
He said that multilateral development banks would be key for global private sector development and should focus on innovative ways to finance small business creation.
"The success of the World Bank in meeting each of these global challenges will depend critically on the institution's global legitimacy," he said.
Last week Mr Geithner told an IMF/World Bank annual meeting in Istanbul that financial institutions needed to concentrate on funding innovative and productive investments rather than the real estate booms of the past.
By Tony Aynsley