The site of the building originally housed the neo-Gothic monastery complex of the Sisters of Our Lady of Mercy (founded in 1862), which was designed by Charles Zaremba and was built between 1889–1891. In 1966, the remains of Sister Faustina were moved to the church. In 1968 Cardinal Karol Wojtyła (later Pope John Paul II) designated the church as a shrine, thanks to the remains of Sister Faustina.