The temple’s main façade is painted in white and is heavily emphasized. The interior is also white, with ceilings and vaults that are treated with a light blue tone, the moldings are golden colored. At certain times of the day, the natural light that goes in through the windows give a celestial aspect. In the ceiling decorations, the symbol of the Heart of May can be seen as well as the “all seeing-eye”.

Among the wall ornamentations, in the presbytery, the seal pertaining to the basilica and that of Pope Pius XI stands out.

The windows and doors have stained glass windows with floral motifs. The stained glass window of the rosette has the image of the Sacred Hearts and is the most important. In the choir, additionally, a Carline organ can be highlighted, but it is not being used.

In the lateral naves we can find the devotional altars, the confessionals and the altarpieces with scenes of the Stations of the Cross in the over pilasters. The altars are of a Corinthian style.

In the right nave great value carvings can be found, such as the image of Saint Michael Archangel, located along one of the pillars; the images of the Virgin of the Carmen also stand out as well as that of Saint Joseph and the Virgin of Andacollo. The nave is presided by the figure of Saint Judas Tadeo, image that arrived from Spain in 1871 and was blessed, along with that of the Virgin of Andacollo and that of the Heart of Mary, on December 5, 1911 by the Archbishop Ignacio González Eyzaguirre. All this imagery is made in polychromatic wood. In this nave, there is also a small image of Saint Antonio de Padua.

In the left nave there other altars with the images of Saint Teresa of Los Andes, the Sacred Heart and Saint Alberto Hurtado; the nave is presided by the image of Saint Antonio Maria Claret. These figures are plaster sculptures and the figure of the Sacred Heart is carved in wood.

The High Altar is presided by a great altarpiece with a Corinthian style and fire gilded; crowned by a Calvary and the large sculptures of Saint Peter and Saint Pablo, it hoses the title holding image of the Heart of Mary, crowned by the Cardinal José Maria on September 3, 1950. This figure is made of polychromatic wood and measures 3.70 meters high and was made by the House Rius of Barcelona and reached Chile in 1898.

The original baptistery is today the small chapel of the 51 Claretian Martyrs of Barbastro, murdered in the 1936 Spanish Revolution and beatified in 1992 by Pope John Paul II.

The paintings of Saint Archbishop Claret, the Burial of the Lord and the Nativity Scene are the oldest, but there is no further information regarding the matter.