The Foursquare Church is an international Pentecostal Christian denomination founded in 1923 by evangelist Aimee Semple McPherson. It lies within the evangelical tradition. Its headquarters are in Los Angeles, California, United States.

The church has its origins in a vision of "Foursquare Gospel" (or "Full Gospel") during a sermon in October 1922 in Oakland, California, by the evangelist Aimee Semple McPherson who was originally an ordained evangelist of the Assemblies of God where she once exerted a large influence until the split. According to chapter 1 of Book of Ezekiel, Ezekiel had a vision of God as revealed to be four different aspects: a man, a lion, an ox and an eagle. It also represents the four aspects of Christ: "Savior, Baptizer with the Holy Spirit, Healer and Soon and Coming King." This was the vision and name she gave at Foursquare Church, founded in January 1923 in Los Angeles, during the dedication of the Angelus Temple in Echo Park, seating 5,300 people. Despite some affinities with Pentecostals, her beliefs are interdenominational. The attendance has become a megachurch with 10,000 people. McPherson was a flamboyant celebrity in her day, participating in publicity events, such as weekly Sunday parades through the streets of Los Angeles, along with the mayor and movie stars, directly to Angelus Temple. She built the temple, as well as what is now known as Life Pacific University adjacent to it, on the northwest corner of land that she owned in the middle of the city.

McPherson's celebrity status continued after her death, with biopics such as the 1976 Hallmark Hall of Fame drama The Disappearance of Aimee depicting her life, as well as the 2006 independent film Aimee Semple McPherson, which particularly focused on her month-long disappearance in May–June 1926 and the legal controversy that followed.

After Aimee Semple McPherson's death in 1944, her son Rolf K. McPherson became president and leader of the church, a position he held for 44 years. The Foursquare Church formed the Pentecostal Fellowship of North America in 1948 in Des Moines, Iowa, in an alliance with the Assemblies of God, the Church of God, the Open Bible Standard Churches, the Pentecostal Holiness Church, and others. In 1994, 46 years after the founding of the Pentecostal Fellowship, it was reorganized as the Pentecostal/Charismatic Churches of North America after combining with African-American organizations, most significantly the Church of God in Christ.

In 1968, the Calvary Chapel Costa Mesa congregation of the International Church of the Foursquare Gospel (under pastor Chuck Smith) broke from the denomination and later formed an association of autonomous Charismatic Evangelical churches, today making up the Charismatic but non-Pentecostal denomination, Calvary Chapel.

On May 31, 1988, John R. Holland became the Church's third president and held the position until July 1997.

Harold Helms served as interim president from July 1997 to July 1998 and was followed by Paul C. Risser, who became the president on April 16, 1998, at the church's 75th annual convention.

In October 2003, under Risser's tenure, the church sold the Los Angeles radio station KFSG-FM to the Spanish Broadcasting System for $250 million. Risser's leadership led to another high-profile controversy for the church, when, without the involvement of the denomination's board of directors and finance council, church funds were invested in firms that targeted the "close-knit evangelical community" but turned out to be Ponzi schemes. Risser resigned his leadership position under fire in March 2004.