Missouri's third congressional district is in the eastern and central portion of the state. It stretches from the southern part of Columbia (including the University of Missouri) and the state capital of Jefferson City in the west to St. Charles County (including the large suburbs of St. Charles, St. Peters and Wentzville) and western Jefferson County in the east. The district took its current form in 2023, when Cooper and parts of Boone counties were added to the district, while Franklin and most of Warren counties were instead drawn into the 2nd district. Its current representative is Republican Blaine Luetkemeyer.

From 1953 to 2013, the 3rd had been located in the southern portion of the St. Louis area, including the southern third of St. Louis City, and had a dramatically different political history from the current 3rd. Its best-known congressman was Dick Gephardt, who represented the district for 28 years until his retirement from Congress.

Following a dramatic drop in the population of St. Louis in the 2010 United States census, Missouri lost a congressional seat effective in 2013. Redistricting maps indicated that the 3rd district would be dismantled. The 3rd's home base in St. Louis would be absorbed by Missouri's 1st congressional district. Much of the district outside the St. Louis area would be drawn into the 8th district. Meanwhile, the new 3rd included most of the territory currently in the 9th district, which was dissolved.^[3]

• Missouri's congressional districts
• List of United States congressional districts