In 1909, a 27 rank electro-pneumatic organ was built and installed by the Kimball Company of Chicago. It was rebuilt by Schoenstein of San Francisco in 1953.

By the mid 1980's, this organ had come to the end of its natural life and was replaced in 1992 by a new 77/79 rank mechanical action English-style organ built by Kenneth Jones and Associates of Bray, Ireland.

The organ, which has 4,066 pipes, stands in a Gothic case designed to match the woodwork installed in the Comes interior of 1918.

A notable element of the organ is the Fanfare Trumpet that extends from the front of the choir gallery. The organ serves both liturgical and concert purposes.

Originally designed by F. X. Zettler of the House of Littler, Royal Bavarian Institute in Munich, Germany, and installed in 1908, the windows in the body of the Cathedral were completely rebuilt in 1992 by Rohlf Studios of New York. The windows on the west side (from back to front) portray the Joyful Mysteries of the Rosary (The Annunciation, The Visitation, The Nativity, The Presentation of Jesus, and the Finding of the Child Jesus in the Temple). The last of these is portrayed in the large west transept window, at the top of which is a scene of the woman, reputed to be St. Mary Magdalene, washing the feet of Jesus. Represented around this scene are (clockwise form the top) St. Gregory, St. Matthew, St. Jerome, St. Mark, St. Augustine, St. Luke, St. Ambrose, and St. John.

The windows on the east side (from front to back), beginning with the large east transept window, depict the Glorious Mysteries of the Rosary (The Resurrection, The Ascension, The Descent of the Holy Spirit, The Assumption of Mary, and The Crowning of Mary as Queen of Heaven). The Resurrection window also contains a medallion of Christ appearing to St. Mary Magdalen. Around this scene are (clockwise from the top) St. Farancis de Sales, St. Agnes, St. Stephen, St, Ignatius, St. Francis of Assisi, St. Bernard, St. Vincent de Paul, and St. Monica.

The two windows in the Blessed Sacrament chapel were designed by George W. Sotter of Pittsburgh in 1918 and display images of the twelve apostles. These windows exhibit a distinctly different style of stained glass from that in the body of the church. At the rear of the Cathedral above the organ is the great Rose Window depicting St. Cecilia, patroness of music, surrounded by angels with musical instruments.

The altar, the central element in a Catholic church and the focal point of liturgical events, is built of Carrara onyx and inlaid with glass mosaic. It stands on a chancel (marble floor) designed to highlight and heighten its centrality and significance. The placement of the altar at the crossing marks its identity as the center and heart of the Cathedral. The centrality of the altar is further defined by four large chandeliers that hang in its vicinity. These, along with the other chandeliers and light fixtures, were designed by Roger Morgan, of New York, and installed in 1993. The altar contains relics of St. Gratus, Bishop of Aosta in Piedmont, Northern Italy, who died in 457, and St. Fenusta, an early Roman martyr buried in the Roman catacombs. The relics signify the call to sainthood of all who approach Christ's table and the link across space and time between every eucharist. The altar is visually related to the baptismal font, both in materials and style, symbolizing the close relationship between baptism and the Mass.

The two confessionals at the rear of the cathedral originally carved by William F. Ross and Company of East Cambridge, Massachusetts, and installed in 1918, were reconstructed in 1993 to more ample proportions to facilitate both face-to-face confession and confession behind a screen. Significantly, the confessionals flank the baptismal font to symbolize the nature of sacramental confession as a renewal of baptismal commitment.

Inside the inner back doors are shrines to two saints well known for their charitable work. On the east side is the statue of St. Anthony of Padua, carved by Henry Schmitt of Buffalo in 1918. On the west is a statue of St. Vincent de Paul, the founder of the Vincentians, (the order to which Bishop Glass belonged), carved in 1993 by Agrell and Thorpe, Ltd., Sausalito, California. These shrines symbolize the cathedral's commitment to charity and service to the poor.

The baptismal font, made of Carrara onyx and glass mosaic, combines a traditional-style upper font with a lower font. The lower baptismal font is patterned after fonts used in the early centuries of the Catholic Church. The font, dedicated in 1993, combines the symbolism of the octagon (signifying the "eighth day" of eternity), the cross (signifying Jesus' death and resurrection) and, at the center of the lower font, an ornate pattern that can read as paradise, a crown, the sun, the tree of life, or the axis mundi (center of the world.) The lower font responds to the efforts of the Second Vatican council to restore early Christian baptismal practices and accommodates both the pouring of water and immersion.

The interior of the Cathedral has gone through three phases. the first interior (1909-1918) was quite simple with white walls and green columns.

The second interior was created under the leadership of Joseph S. Glass, who became the second Bishop of Salt Lake City in 1915. A man of strong artistic sensibility, Bishop Glass undertook a thorough reconstruction of the art and furnishings, inspired by the Spanish gothic art of the late Middle Ages. The colorful murals in the sanctuary and transepts were added at that time, as was the ornate and dramatic coloration evident throughout the building. This interior was completed before Christmas, 1918.

Under the leadership of William K. Weigand, seventh Bishop of Salt Lake City (1980-1994), the restoration of the second interior, which had suffered the effects of dirt and pollution, was planned and executed. This included the renovation of the liturgical elements of the Cathedral to bring them into conformity with he liturgical reforms that followed Vatican Council II. It was completed in 1993.

Formerly the baptistery, the chapel is on the east side of the main exit from the Cathedral. It houses the statue acquired in 1993. Madonna and Child by Utah artist Avard Fairbanks. It also contains six original stained glass windows from the early part of this century and two new windows described as the "Vatican II windows." Installed in 1993, the new windows celebrate two of the most important achievements of the Second Vatican Council: the ecumenical movement, symbolized by the standard ecumenical emblem, and the church's commitment to dialogue with the modern world, symbolized by the United Nations' symbol and the words "Lumen Gentium" referring to the church as the light to the nations. The statue of St. Mary Magadalen, carved in the late 1940's by Canadian artist Gordon Newby, is also housed in this room.

The result of seven years of labor, the tympanum above the main doors is the work of Francis Aretz of Pittsburgh, Pennsylvania. Shipped in several pieces to Salt Lake City in 1917, the tympanum features the figure of Christ as High Priest, flanked by an angel on each side; and the Twelve Apostles, six standing and six kneeling, each with his appropriate symbol. The four great Doctors of the Church, Saints Jerome, Ambrose, Gregory and Augustine, appear in the upper half of the work. The four Evangelists, Saints Matthew, Mark, Luke and John appear surrounding the arms of the central cross.

Eight gargoyles look down from the 185-feet-high east and west towers. The gargoyles are primarily decorative, and do not serve as water spouts as do those on many of the cathedrals of Europe. The original gargoyles placed on the Cathedral in 1917 weathered and eroded to the extent that hey were nonexistent by 1930. In the 1975 restoration, eight new steel-reinforced gargoyles, weighing 1,200 pounds each, were placed on the Cathedral. Each gargoyle, made by University of Utah art student Peter Cole, represents a petrified combination of a bird, a dog and a cat.