The parish of Leszno was established in 1776, following the withdrawal of a 1525 decree which prohibited the settlement of dissenters in the region of Mazovia. The following year, the first Reform Church, which now serves as the headquarters of the Warsaw Chamber Opera, was built and designed by architect Szymon Bogumił Zug. In addition, a rectory was also built at this time.
On October 30, 1866, the construction of a new church in the Gothic style began, designed by architect Adolf Loewe. The construction process took 14 years to complete and the church was finally dedicated on October 24, 1880. One of the notable features of the church is its high tower with a shawl helmet, which is modeled after the tower of the Cathedral of Our Lady in Freiburg im Breisgau. Another unique aspect of the church is its oak pulpit, which was made and designed by Konstanty Wojciechowski.
In 1881, the parish founded by the Działyński Palace included various facilities, such as a hospital, an elementary school, an orphanage, and a nursing home, all aimed at serving the community.
After achieving independence, the community life in the parish underwent a rapid transformation. This led to the creation of several organizations aimed at engaging the youth and promoting spiritual development. The Youth Association, Mission Inner Circle, and Ladies Auxiliary were established, and they all played a crucial role in organizing Sunday school classes for the children in the parish.
Additionally, the organizations arranged trips to places outside the city and held camping activities for kids on property that had been donated to the church. To keep the members informed and engaged, two parish magazines were published during this time. "Żagiew Chrystusowa" (The Torch of Christ) was in circulation from 1924 to 1928, while "Jednota" (Unity) was published from 1926 to 1939. These magazines served as an important medium of communication, and they helped to foster a sense of unity and community among the members of the parish.
In 1940, the structures belonging to the parish, including the church, the Działyński Palace, the hospital, and various other buildings located in the "Evangelical enclave" near the Warsaw ghetto, were devastated during the Battle of Warsaw in September 1939. Despite the danger, the parishioners and clergy members made efforts to rescue Jews from the ghetto, which is remembered by a memorial located within the boundaries of the ghetto and behind the parish.
Throughout the occupation, numerous members of the parish lost their lives, and several priests were senselessly murdered. Additionally, Evangelicals also participated in the Warsaw Uprising, demonstrating their bravery and determination.
The first church services took place in the Methodist chapel in Savior Square. The church on Aleja Solidarności, which served Warsaw's Lutherans whose church was burned down in 1939, underwent renovations. In 1958, the original Zug-designed church was restored and became the headquarters of the parish rectory. In 1957, the "Unity" magazine was reactivated by the editors. From 1960 to 1974, the Polish Ecumenical Council was headquartered there.
The pastor of the church is currently Michał Jabłoński. The position of the parish administrator is filled through an election process conducted by the College Church. This election occurs every three years and involves members of the church, including the pastor, who holds a ten-year term. The College Church and pastor then choose the General Assembly, which is responsible for religious education for children and adolescents. This education takes place in various forms such as Sunday school, lessons before confirmation, and a two-year course for youth after confirmation.
The parish also caters to the spiritual needs of foreign nationals of Chinese and Vietnamese nationalities. In addition to its religious services, the parish operates several musical groups, including the Chamber Choir of the Reformed Evangelical Church in Warsaw. This choir has been active since 1991 and has performed at the church, as well as at other churches of different denominations. It has also participated in international competitions in countries such as the Czech Republic, Finland, Germany, Romania, Slovakia, and Switzerland.
The parish also operates the Concerto Polacco orchestra and the Sine Nomine choir, which specialize in performing classical musical works. These groups provide a unique form of artistic expression for members of the parish and contribute to the cultural landscape of the community.