The 1800 United States presidential election in Pennsylvania took place on December 1, 1800 during a special session of the Pennsylvania General Assembly. Members of the bicameral state legislature chose 15 electors to represent Pennsylvania in the Electoral College as part of the 1800 United States presidential election. Eight Democratic-Republican electors and seven Federalist electors were selected. Unlike in the previous election, when one elector split his ballot between Republican Thomas Jefferson and Federalist Thomas Pinckney, all 15 electors followed the party line, with the Republicans voting for Jefferson and the Federalists for incumbent President John Adams. This was the first and only U.S. presidential election in which Pennsylvania's electors were not chosen by popular vote.

The 1800 United States presidential election was the fourth quadrennial presidential election. It was held from October 31 to December 3, 1800. In what is sometimes called the "Revolution of 1800", the Democratic-Republican Party candidate, Vice President Thomas Jefferson, defeated the Federalist Party candidate and incumbent, President John Adams. The election was a political realignment that ushered in a generation of Democratic-Republican leadership. This was the first presidential election in American history to be a rematch.