The 27th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C., between March 4, 1841, and March 4, 1843, during the one-month presidency of William Henry Harrison and the first two years of the presidency of his successor, John Tyler. The apportionment of seats in the House of Representatives was based on the 1830 United States census. Both chambers had a Whig majority, making the 27th Congress the only Whig-controlled Congress of the Second Party System.

This list is arranged by chamber, then by state. Senators are listed in order of seniority, and representatives are listed by district.

Senators were elected by the state legislatures every two years, with one-third beginning new six-year terms with each Congress. Preceding the names in the list below are Senate class numbers, which indicate the cycle of their election. In this Congress, Class 1 meant their term began in the last Congress, requiring re-election in 1844; Class 2 meant their term began with this Congress, requiring re-election in 1846; and Class 3 meant their term ended with this Congress, requiring re-election in 1842.

The count below reflects changes from the beginning of the first session of this Congress.

Lists of committees and their party leaders.