The oath of office of the President of the United States is the oath or affirmation that the President of the United States takes upon assuming office. The wording of the oath is specified in Article II, Section One, Clause 8, of the United States Constitution, and a new president must take it before exercising or carrying out any official powers or duties.

This clause is 1 of 3 oath or affirmation clauses in the Constitution, but it is the only one that actually specifies the words that must be spoken. The Presidential oath requires much more than that general oath of allegiance and fidelity. Before he or she enters on the Execution of his Office, he or she shall take the following Oath or Affirmation:

"I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States."