Overall, the church’s interior has maintained its medieval appearance. It has a longitudinal plan and decorated wooden beams on the ceiling, a possible reference to Noah’s Ark , the ark of salvation. The single chamber structure has excellent acoustic properties, enabling everyone to follow the prayers and listen to the sermons and precepts of the Christian doctrine.
A common trait of these churches is the square apse termination, covered by a cross vault whose starry sky decoration evokes the Creation. Inside is a wooden choir made in 1687: it is one of the characteristic features, important to Carmelite life as the friars would gather here to pray during the day and to take part in liturgical ceremonies. Two wooden doors, carved with the three theological virtues of Faith, Hope, and Charity and with the allegory of religion separate the choir from the nave where the faithful gathered.
The step that runs along the walls of the nave was used either to access the side altars or the Chapel of the Holy Sacrament when the church was crowded or as a dividing element between the area for the congregation and the sacred area of the side altars, because it is important to remember that even these were reserved for Mass and prayers.
Of the many side altars erected in the church in past centuries, only three have survived to this day: one is located along the left wall, near the side entrance, and is surmounted by the Ascension of Jesus, by Girolamo del Pacchia; the other two against the right wall respectively house the fresco of the Assumption of the Virgin Mary, attributed to Benedetto di Bindo and a masterpiece by Beccafumi, the beautiful altarpiece Saint Michael the Archangel Banishing the Fallen Angels; this last altar contains the relics of Blessed Franco Lippi da Grotti.
Further along the right wall there is the entrance to the Chapel of the Holy Sacrament, where the Carmelites, who are extremely devoted to the Holy Eucharist, spent much of their time in worship. A second altar was erected on the right side of the chapel for another Eucharistic tabernacle and a painting on board portraying Saint Thérèse of Lisieux, who was particularly devoted to the Holy Sacrament in the centre.
The high choir is located above the chapel entrance, and is used by the friars for prayers at night or in winter as it has direct access from the dorms. In order to let more light into the nave, eight windows were opened in the walls, four of which are blind because of the construction of the greater cloister. The large window in the apse, made, like the others, by the Florentines Ulisse and Sergio De Matteis, bears the image of Our Lady of Mount Carmel on a Throne with the Holy Child, while the other smaller one represents the stem of the Congregazione del Suffragio, who ran the church from 1873 for almost one hundred years. Above the apse, the great central rose window bears the half-bust portrait of the Blessing Redeemer, with the symbols of the four Evangelists around him. The Coat of Arms of the Carmelite Order is placed in an opening of the façade while those of the convent’s benefactors surround it.