The United States Senate Committee on Appropriations, informally known as the Senate Appropriations Committee, is a standing committee of the United States Senate. It has jurisdiction over all discretionary spending legislation in the Senate.

The Senate Appropriations Committee is the largest committee in the U.S. Senate, with 30 members in the 117th Congress. Its role is defined by the U.S. Constitution, which requires "appropriations made by law" prior to the expenditure of any money from the Treasury, and the committee is therefore one of the most powerful committees in the Senate.^[1] The committee was first organized on March 6, 1867, when power over appropriations was taken out of the hands of the Finance Committee.^[2]

The chair of the Appropriations Committee has enormous power to bring home special projects (sometimes referred to as "pork barrel spending") for their state as well as having the final say on other senators' appropriation requests.^[3] For example, in fiscal year 2005, per capita federal spending in Alaska, the home state of Chair Ted Stevens, was $12,000, double the national average. Alaska has 11,772 special earmarked projects for a combined cost of $15,780,623,000. This represents about four percent of the overall spending in the $388 billion Consolidated Appropriations Act of 2005 passed by Congress.^[4]

From 2001 to 2021, every Senate Majority Leader was a previous or concurrently serving member of the Appropriations Committee: Tom Daschle (committee member, 1991–1999; majority leader, 2001–2003), Bill Frist (committee member, 1995–2002; majority leader, 2003–2007), Harry Reid (committee member, 1989–2006; majority leader, 2007–2015), and Mitch McConnell (current committee member; majority leader, 2015–2021).

The federal budget is divided into two main categories: discretionary spending and mandatory spending. Each appropriations subcommittee develops a draft appropriations bill covering each agency under its jurisdiction based on the Congressional Budget Resolution, which is drafted by an analogous Senate Budget committee. Each subcommittee must adhere to the spending limits set by the budget resolution and allocations set by the full Appropriations Committee, though the full Senate may vote to waive those limits if 60 senators vote to do so. The committee also reviews supplemental spending bills (covering unforeseen or emergency expenses not previously budgeted).

Each appropriations bill must be passed by both houses of Congress and signed by the president prior to the start of the federal fiscal year, October 1. If that target is not met, as has been common in recent years, the committee drafts a continuing resolution, which is then approved by Congress and signed by the president to keep the federal government operating until the individual bills are approved.

In accordance of Rule XXV of the United States Senate, all proposed legislation, messages, petitions, memorials, and other matters relating to the following subjects is referred to the Senate Committee on Appropriations:

Likewise, Article I, Section 9, Clause 7 of the United States Constitution, clearly vesting the power of the purse in Congress, states: "No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law...and a regular Statement and Account of the Receipts and expenditures of all public Money shall be published from time to time." This clause is the foundation for the congressional appropriations process and the fundamental source of the Senate Appropriations Committee's institutional power – as is the same with its counterpart in the lower house. In other words, Article I, Section 9, Clause 7 of the United States Constitution charges the United States Congress with the legislative duty of controlling government spending separate from the executive branch of government – a significant check and balance in the American constitutional system.