The 1804 United States presidential election in Pennsylvania took place as part of the 1804 United States presidential election. Voters chose 20 representatives, or electors to the Electoral College, who voted for President and Vice President.

The 1804 United States presidential election was the fifth quadrennial presidential election, held from Friday, November 2, to Wednesday, December 5, 1804. Incumbent Democratic-Republican president Thomas Jefferson defeated Federalist Charles Cotesworth Pinckney of South Carolina. It was the first presidential election conducted following the ratification of the Twelfth Amendment to the United States Constitution, which reformed procedures for electing presidents and vice presidents.