The presidential transition of Barack Obama began when he won the United States presidential election on November 4, 2008, and became the president-elect. Obama was formally elected by the Electoral College on December 15, 2008. The results were certified by a joint session of Congress on January 8, 2009, and the transition ended when Obama was inaugurated at noon EST on January 20, 2009.

In the United States, a presidential transition is the process during which the president-elect of the United States prepares to take over the administration of the federal government of the United States from the incumbent president. Though planning for transition by a non-incumbent candidate can start at any time before a presidential election and in the days following, the transition formally starts when the General Services Administration (GSA) declares an “apparent winner” of the election, thereby releasing the funds appropriated by Congress for the transition, and continues until inauguration day, when the president-elect takes the oath of office, at which point the powers, immunities, and responsibilities of the presidency are legally transferred to the new president.