Redistricting in Pennsylvania refers to the decennial process of redrawing state legislative and federal congressional districts in the U.S. state of Pennsylvania.

Before the 2000 election, the Pennsylvania House of Representatives was evenly split with 100 members from the Republican and Democratic parties and 3 vacancies. After the 2000 election, there were 104 Republican house seats and 99 Democratic seats. Republicans also maintained control of the Pennsylvania State Senate, with 30 Republican seats and 20 Democratic seats. Republicans also controlled the Pennsylvania governorship. This would ensure the 2000 census redistricting process was led by the Republican-controlled Pennsylvania General Assembly. Following the 2000 census, Pennsylvania Republicans would have full state control of the redistricting process.

Pennsylvania Senate Bill 1200 was introduced by Republican State Senators Brightbill and Lemmond on November 16, 2001. On December 10, 2001, the Senate considered amendments to Senate Bill 1200. A Republican amendment was ultimately agreed to. The version of Senate Bill 1200 that eventually passed the Senate contained a population deviation of twenty-four persons. After an amendment by the Pennsylvania House of Representatives, that chamber passed Senate Bill 1200 on December 12, 2001. The version of Senate Bill 1200 that passed the House had a total population deviation of nineteen persons. It also maintained two minority-majority districts in the Philadelphia area, created one open seat in the southeastern part of the Commonwealth and paired two Democratic incumbents in the same district. One Democratic incumbent was paired against one Republican incumbent. The Senate refused to concur in the amendments to Senate Bill 1200 offered by the House of Representatives. A Conference Committee was appointed and a plan was eventually devised that contained a nineteen-person deviation. This Conference Committee Report on Senate Bill 1200 was passed by the Senate on January 3, 2002 and by the House of Representatives later the same day. It was signed into law by Governor Mark Schweiker on January 7, 2002.

In Vieth v. Jubelirer, a United States Supreme Court case challenging the constitutionality of the 2000 redistricting process, the Supreme Court was unable to agree upon a legal standard for judging when partisan gerrymandering violated the United States Constitution.

After the 2000 elections, Pennsylvania Republicans held a slim 11 to 10 congressional seat majority over the Democrats. In the 2002 Pennsylvania House of Representatives elections:

This would be maintained until the 2006 Democratic wave election, when Democrats won 11 of the 19 elections for the United States House of Representatives.

In the 2010 Pennsylvania elections, Republicans won a landslide victory, with Tom Corbett winning the 2010 Pennsylvania gubernatorial election, recapturing the Pennsylvania House of Representatives, and regained their majority in House of Representatives in Pennsylvania, winning 12 seats to the Democrat's 7 seats. Following the 2010 census, Pennsylvania Republicans would have full state control of the redistricting process for the second decade in a row.

On September 14, 2011, Republican senate leadership introduced a congressional redistricting bill which contained neither a map nor description of proposed congressional district lines. The proposed lines were added in the senate State Government Committee on December 13, 2011. The committee approved the bill 6-5 along party lines. Breaking with his party, Republican Sen. Mike Folmer opposed the Republican bill, saying "all you have to do is look at (the map)" to see it appeared to be specifically drawn to dilute Democratic votes and was the perfect example of why redistricting reform is needed. Barry Kauffman, lobbyist for Common Cause of Pennsylvania, agreed with Folmer, saying the plan "is a clear-cut case of politicians picking their voters in order to prevent voters from having a meaningful opportunity to pick their elected officials".