The church is painted inside entirely in white, over which several both white and golden decorative elements are added. Decoration is mainly architectural. It comprises pilasters ending up in acanthus leaves decorating the separation between semicircular arches, festoons in the upper friezes, and vegetal-inspired elements. Vault is divided into molded panels, with a symmetrical geometric development, where a vegetal-influenced decoration is generated. Contrast between figure and background is through color: cyan for the background and golden for figures. The walls are decorated with oil paintings of the Stations of the Cross that were brought from Rome and donated by Felipe Ossa Ceroz.

The main altar, entirely golden-colored, has in its central part one of several valuable big-sized paintings.

The church has big-sized pictorial works created by different artists that are a part of the Jesuit heritage. The painting, by artist Pietro Galiardi, in the main altar is devoted to the Immaculate Conception of Virgin Mary. On both sides of the main altar, as a transept, there are minor altars also depicting pictorial works representing: Saint Ignatius of Loyola, founder of the Jesuit order, painting by Francesco Grandi; as well as other paintings by Claudio Di Girólamo portraying Saint Francis Xavier and Saint Alberto Hurtado.

The temple conserves a large mixed pipe organ that has as a central core a small Cavaillé-Coll. With its three manual keyboards and 33 registrations, it is one of the largest pipe organs in Chile.

Underneath the altar where Saint Ignatius’ portrait is, there are the relics from Saint Marius, Persian , who together with his family came from Persia to Rome in the 3rd century, where they were martyred for sympathizing with and burying the bodies of Christians. Relics were brought to Chile and deposited in the temple as a way of increasing veneration of the saint in the country.