The exterior of St Martin's reflects the Gothic Revival interpretation of the Early English style associated with 13th century churches.
 Its most notable exterior feature is its considerable height, accentuated by the modest height of the majority of the surrounding buildings; brown brick, offset in some places with red, predominates on the outside, and the layout of the church is standard: an aisled nave with chapels on each side, and a chancel.
 A saddleback tower was included in the original plans but never built: a small bell-arch with a single bell was built instead, towards the north end.
 The church is on a north-south (liturgical east-liturgical west) alignment parallel with the Lewes Road.

The church floor lies six feet below street level, creating an architectural illusion of being larger internally and from the entrance there is an unimpeded view across the nave and into the chancel.
Octagonal stone columns topped by brick arches separate the aisles from the nave; above these arches are a series of clerestory windows.
A large series of stained windows dominates the west wall.
A series of 144 painted shields adorn the nave ceiling, representing the Anglican missionary dioceses founded within 100 years of the church.

Although the marble altar is not original, dating from 1949, the large reredos above it is.
 It consists of 20 pictures and 69 statues, all of which were carved in the German town of Oberammergau, noted worldwide for its woodcarving tradition.
 The original pulpit, surmounted by a unique canopy tapering to 55 feet and dating from 1880, also remains: this, and the font in the raised entrance area, are decorated with materials from the collection of Henry Wagner.
 The base of the pulpit contains olive wood collected from the Mount of Olives; and the font, built of Sussex marble and installed in 1907, contains a variety of other stones and marble from sites such as Cairo and Pompeii, brought back to England by Wagner himself during his lifetime.
The exterior of St Martin's reflects the Gothic Revival interpretation of the Early English style associated with 13th century churches.  Its most notable exterior feature is its considerable height, accentuated by the modest height of the majority of the surrounding buildings; brown brick, offset in some places with red, predominates on the outside, and the layout of the church is standard: an aisled nave with chapels on each side, and a chancel.  A saddleback tower was included in the original plans but never built: a small bell-arch with a single bell was built instead, towards the north end.  The church is on a north-south (liturgical east-liturgical west) alignment parallel with the Lewes Road.
The church floor lies six feet below street level, creating an architectural illusion of being larger internally and from the entrance there is an unimpeded view across the nave and into the chancel. Octagonal stone columns topped by brick arches separate the aisles from the nave; above these arches are a series of clerestory windows. A large series of stained windows dominates the west wall. A series of 144 painted shields adorn the nave ceiling, representing the Anglican missionary dioceses founded within 100 years of the church.
Although the marble altar is not original, dating from 1949, the large reredos above it is.  It consists of 20 pictures and 69 statues, all of which were carved in the German town of Oberammergau, noted worldwide for its woodcarving tradition.  The original pulpit, surmounted by a unique canopy tapering to 55 feet and dating from 1880, also remains: this, and the font in the raised entrance area, are decorated with materials from the collection of Henry Wagner.  The base of the pulpit contains olive wood collected from the Mount of Olives; and the font, built of Sussex marble and installed in 1907, contains a variety of other stones and marble from sites such as Cairo and Pompeii, brought back to England by Wagner himself during his lifetime.
St Martin's Church, Brighton