The foundation stone of the church was laid in October 1861. The church was completed and consecrated in October 1863. The tower and spire were added four years later. The architect Charles Hansom, designer of some fifty Catholic churches in the country and brother of Joseph Aloysius Hansom, the designer of the Hansom Cab, regarded St John's as his best and most rewarding work. The church, on the site of an earlier priory, was built by the Benedictines of Downside Abbey who handed it over to the Clifton Diocese in 1932.

St John's prospered from its consecration until the Second World War when, on 27th April 1942, during the second night of a German air attack on Bath, the presbytery received a direct hit and was destroyed. Fr Sheridan, one of the curates, the housekeeper and three members of the Sweet Family (sheltering after a previous raid) were killed. The church was severely damaged, the south aisle being completely demolished.
  

The church is built in the decorated Gothic style with Bath stone used throughout the entire building. The masonry is rustic work in courses. The internal measurements are 140' by 60' increased at the Transept to 73'; the stone tower and spire stand 222' high, being the highest in Bath. The walls are faced on both sides with free stone. The chancel is the same height and width as the nave, and it is terminated by a semi- octagonal apse; on each side of the chancel are chapels which are connected by moulded arches, resting on marble shafts. On the exterior, the aisle roof, unlike the usual plain straight line, is broken up into gables, one rising over each window and over the Lady Chapel, Transept and Baptistry.

Looking toward the Sanctuary one sees the two rows of polished Devon Marble pillars separating the Nave from the two aisles. Ancaster stone capitals surmount the pillars with elaborate carvings of natural foliage including various flowers and fruits. In the spandrels between the arches are circular panels of carved angelic figures playing upon musical instruments.

The High Altar is of white marble on coloured marble columns and contains the Holy Relics of St Justina of Padua. The four panels of the reredos illustrate scenes from the life of St John the Evangelist
(1) His giving Communion to the Virgin Mary upon her death,
(2) His Martyrdom,
(3) His vision and writing of the Apocalypse and
(4) His being carried to church by his disciples.
Three stone carvings beneath the altar slab represent the Descent of the Holy Spirit, the Agony in the Garden and the transfiguration. Above the High Altar rise three stained glass windows of the apse, the centre one showing the Virgin Mary and St John on either side of the Crucifixion. The window to the left shows the Resurrection and that on the right the Ascension. The wrought iron screen at the front of the Sanctuary carries, under the rood, the emblem of Jesus Christ, a pelican feeding its young with its own blood.

(left of the Sanctuary)
The altar, brought from an earlier church in Bath with a highly decorated reredos, has a frontal illustrating the presentation of the Virgin Mary in the Temple. The great Cardinal Newman is reputed to have celebrated Mass in this chapel whilst visiting Bath.

(right of the Sanctuary)
The central panel of the altar frontal is the scene of the Last Supper and on , either side are depicted the sacrifices of Melchisedech and Abraham: In the centre, over the tabernacle with its conical roof, the pelican is seen again feeding its young with its own blood.

Bells