Sacred Heart follows a basilica plan with a corner tower.
The foundation is composed of Anamosa Limestone and the walls of the structure are brick, clad in rock-faced Bedford stone quarried in Indiana.
The nave is nine bays in length, and they are divided by buttresses.
The first bay is the tower section.
The other bays contain either a tracery or paired lancet window, which alternate down the nave.
The church measures 180 feet (55 m) in length and its nave is 65 feet (20 m) wide.
Across the back, where the sacristy and St. Margaret's chapel are located, it is 80 feet (24 m) wide.
The roof rises 75 feet (23 m) above the ground and the spire on top of the tower is 160 feet (49 m) tall.
When it was completed the cathedral was the tallest structure in the Quad Cities.

The church features an open interior without columns.
There is an extensive amount of woodwork in the interior, including the altars, pews, ceiling, wainscoting, and the gallery frontal.
There are four sets of oak pews across the width of the church.
The vaulted ceiling is supported by hammer beams.
The reliefs below the old high altar depict the sacrifice of Able, Abraham and his son Isaac, and the priest Melchizedek.
The three Old Testament images are found in the Roman Canon.
The statues of St. Peter and St. Paul were added later.
Gold reliquaries that contain relics of various saints are in nooks on either side of the reredos.
The shrine of the Blessed Virgin Mary on the left side of the church contains statues of St. Benedict on the left and St. Thomas Aquinas on the right, that were added in 1902.
At the base of the altar is a relief of the Dormition of the Virgin.
The St. Joseph shrine contains statues of St. Ignatius of Loyola on the left and St. Anthony of Padua on the right that were also added in 1902.
At the base of the altar is a relief of Joseph on his deathbed with Mary and Jesus at his side.
Initially, the bishop's throne was placed in the archway on the left side of the sanctuary.
The large stations of the cross are bas reliefs with wood frames that line the side walls of the church.
They were installed in 1892.

The stained glass windows feature bright colors that were chosen by Bishop Cosgrove.
The tall windows on the sides of the nave depict the Twelve Apostles.
The rose window on the front of the church includes the following Christian images: an anchor for hope, wheat for bread, a crown for Christ the King, keys for the Apostle Peter, a dove for the Holy Spirit, the cross and crown for the crucifixion, the chalice and bread for the Holy Communion, and a harp for music and worship.
The large window over the altar depicts Jesus appearing to St. Margaret Mary Alacoque, who spread the devotion to the Sacred Heart of Jesus.

Electric lights were installed in the sanctuary in 1895.
A renovation of the cathedral's interior was completed in 1907.
It included a frescoing of the interior, enlarging the choir loft, and adding six hundred new lights.
Sacred Heart follows a basilica plan with a corner tower. The foundation is composed of Anamosa Limestone and the walls of the structure are brick, clad in rock-faced Bedford stone quarried in Indiana. The nave is nine bays in length, and they are divided by buttresses. The first bay is the tower section. The other bays contain either a tracery or paired lancet window, which alternate down the nave. The church measures 180 feet (55 m) in length and its nave is 65 feet (20 m) wide. Across the back, where the sacristy and St. Margaret's chapel are located, it is 80 feet (24 m) wide. The roof rises 75 feet (23 m) above the ground and the spire on top of the tower is 160 feet (49 m) tall. When it was completed the cathedral was the tallest structure in the Quad Cities.
The church features an open interior without columns. There is an extensive amount of woodwork in the interior, including the altars, pews, ceiling, wainscoting, and the gallery frontal. There are four sets of oak pews across the width of the church. The vaulted ceiling is supported by hammer beams. The reliefs below the old high altar depict the sacrifice of Able, Abraham and his son Isaac, and the priest Melchizedek. The three Old Testament images are found in the Roman Canon. The statues of St. Peter and St. Paul were added later. Gold reliquaries that contain relics of various saints are in nooks on either side of the reredos. The shrine of the Blessed Virgin Mary on the left side of the church contains statues of St. Benedict on the left and St. Thomas Aquinas on the right, that were added in 1902. At the base of the altar is a relief of the Dormition of the Virgin. The St. Joseph shrine contains statues of St. Ignatius of Loyola on the left and St. Anthony of Padua on the right that were also added in 1902. At the base of the altar is a relief of Joseph on his deathbed with Mary and Jesus at his side. Initially, the bishop's throne was placed in the archway on the left side of the sanctuary. The large stations of the cross are bas reliefs with wood frames that line the side walls of the church. They were installed in 1892.
The stained glass windows feature bright colors that were chosen by Bishop Cosgrove. The tall windows on the sides of the nave depict the Twelve Apostles. The rose window on the front of the church includes the following Christian images: an anchor for hope, wheat for bread, a crown for Christ the King, keys for the Apostle Peter, a dove for the Holy Spirit, the cross and crown for the crucifixion, the chalice and bread for the Holy Communion, and a harp for music and worship. The large window over the altar depicts Jesus appearing to St. Margaret Mary Alacoque, who spread the devotion to the Sacred Heart of Jesus.
Electric lights were installed in the sanctuary in 1895. A renovation of the cathedral's interior was completed in 1907. It included a frescoing of the interior, enlarging the choir loft, and adding six hundred new lights.
Sacred Heart Cathedral (Davenport, Iowa)