The Appointments Clause of the United States Constitution empowers the president of the United States to nominate and, with the advice and consent (confirmation) of the United States Senate, appoint public officials. Although the Senate must confirm certain principal officers (including ambassadors, Cabinet secretaries, and federal judges), Congress may by law invest the appointment of "inferior" officers to the President alone, or to courts of law or heads of departments.

The Appointments Clause appears at Article II, Section 2, Clause 2 and provides:

... and [the President] shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments.

The president has plenary power to nominate political appointees, and the Senate's role is only advisory to the nomination, because the president is not bound to appoint his own nominee even with their advice. As Gouverneur Morris stated in the Constitutional Convention, "As the President was to nominate, there would be responsibility, and as the Senate was to concur, there would be security".

The Appointments Clause confers plenary power to the president to nominate, and confers plenary power to the Senate to reject or confirm a nominee, through its advice and consent provision. As with other separation of powers provisions in the Constitution, the wording here seeks to ensure accountability and preempt tyranny. Alexander Hamilton defended the use of a public confirmation of officers in Federalist No. 77, where he commented "a conclave in which cabal and intrigue will have their full scope. ... [T]he desire of mutual gratification will beget a scandalous bartering of votes and bargaining for places." This separation of powers between the president and Senate is also present in the (immediately preceding) Treaty Clause of the Constitution, which gives international treaty-making power to the president, but attaches to it the proviso of the Senate's advice and consent.

Several framers of the U.S. Constitution explained that the required role of the Senate is to advise the president after the nomination has been made by the president. Roger Sherman believed that advice before nomination could still be helpful. Likewise, President George Washington took the position that pre-nomination advice was allowable but not mandatory. The notion that pre-nomination advice is optional has developed into the unification of the "advice" portion of the power with the "consent" portion, although several Presidents have consulted informally with senators over nominations and treaties.

The actual motion adopted by the Senate when exercising the power is "to advise and consent", which shows how initial advice on nominations and treaties is not a formal power exercised by the Senate. On November 21, 2013, the Senate changed its rules regarding the number of votes needed to end debate on a presidential nomination and bring it to a vote. Before that date, a minority of senators could engage in a filibuster and block a vote on a nomination unless three-fifths of senators voted to end debate. Under the new rules, a simple majority is all that is needed to end debate. The only exception was for nominations to the Supreme Court of the United States, which could still be blocked from going to a vote by a filibuster, until the Senate rules were again changed on April 6, 2017, during Senate debate on the nomination of Neil Gorsuch to the Supreme Court.

Congress itself may not exercise the appointment power; its functions are limited to the Senate's role in advice and consent, and to deciding whether to vest a direct appointment power over a given office in the president, a head of department, or the courts of law. The framers of the U.S. Constitution were particularly concerned that Congress might seek to exercise the appointment power and fill offices with their supporters, to the derogation of the President's control over the executive branch. The Appointments Clause thus functions as a restraint on Congress and as an important structural element in the separation of powers. Attempts by Congress to circumvent the Appointments Clause, either by making appointments directly, or through devices such as "unilaterally appointing an incumbent to a new and distinct office under the guise of legislating new duties for an existing office", have been rebuffed by the courts.