The church has a rather moderate and simple decoration, which mainly aims at supporting and enhancing architectural elements of the structure. Dominant colors inside are lighten with white: cream and white are combined for generating contrast between figures and the background. Ornamentation was carried out by several important artists of the period, for example, José Miguel Blanco, the first Chilean sculptor that the Government sent to Paris.

Decoration mainly exists in the apse. There is a set of seven vitreaux decorated with geometric motifs in yellow and blue that add light and symbolic drama to the altar. The central one is divided into three panels ending up in pointed arches.

The altar is moderately decorated with a large painting dedicated to Mary Help of Christians, which symbolizes the importance of this church as the main Sanctuary devoted to this patronage.