It was built in an approximation of the 14th- and 15th-century Perpendicular or Late Gothic style, typical of the so-called Commissioners' churches, of which St Peter's was one.

It was not a revival of its style in the manner of Barry's pupil Augustus Pugin, but, as Nikolaus Pevsner described it, remedies this fault by remarkable inventiveness and boldness.

Barry's hexagonal apse was demolished in 1898 to make way for a much larger, straight-ended chancel designed by Somers Clarke and J. T. Mickelthwaite, built-in Sussex sandstone, its warm hue contrasting with the cold, white appearance of the Portland stone in which the rest of the church was built.

The liturgical east side (geographical north) has a window commemorating Queen Victoria, presented to the church on behalf of the people of Brighton[8] using funds raised in the town.

[11] St Peter's parish was legally united with that of the Chapel Royal in North Street from 25 July 1978 by means of an Order in Council.

[12] In December 2007, after a long period of consultation, the Diocesan Pastoral Committee recommended to the Church Commissioners that St Peter's should be made redundant.

[17] St Peter's had a large pipe organ[18] built-in 1888 for the Hampstead Conservatoire of Music by Henry Willis[19] and brought to Brighton in 1910.

The organ features in a recording made in June 1977 when the Choir of Guildford Cathedral gave a concert at St Peter's.

[25][26] Following a period of silence while work was carried out on the tower, the bells rang out for the first time in almost three years on Sunday 18th December 2022.