In its niches are statues of Jesuit saints: Ignatius of Loyola, Francis Xavier, Aloysius Gonzaga, and Stanisław Kostka made by Dawid Heel.

[4] The church interior has a broad, single-nave with two aisles consisting of chapels, as well as the transept with a dome at the intersection, and a short rectangular chancel around the altar, with a semicircular apse covered with a hemispherical vault.

Today, in place of the original 18th century statues, which were very much damaged by acid rain, there are contemporary copies made of the same material by Kazimierz Jęczmyk.

[2][5] Stucco decorations of the interior, mainly on overhead vaults, belong to Giovanni Battista Falconi of Milan who spent most of his adult life working in Poland.

Among the accessories in the interior, a sarcophagus of the Bishop Andrzej Trzebicki from late 17th century stands out prominently, as well as the receptacles of Branicki family (from 1720–1725) and Brzechffs, from 1716 by Bażanka.

[6][7] Every Thursday inside the Church, demonstrations are held of the longest Foucault pendulum in Poland (46,5 m), suspended for the popular display of the Earth's rotation.

Named after the French physicist Léon Foucault, the experimental apparatus consists of a tall pendulum free to swing in any vertical plane.

The actual path of the swing appears to rotate—while in fact the plane is fixed in space, but the Earth rotates under the pendulum once a sidereal day.

The work on the construction of the pantheon began in October 2010 and the official opening of the first part of the complex took place in 2012 on the 400th anniversary of Piotr Skarga's death whose remains were kept in one of the church's crypts.