The medieval church was repaired in 1623, only to be destroyed in the Great Fire of London in 1666. Rebuilding was not immediate, but was largely completed by 1680, finished in 1703. In 1669 a Roman tombstone, now in the Ashmolean Museum, was found. The current design is topped by a lead-covered octagonal cupola supporting a balcony and tapered spire rising to a height of 158 ft (48 m).
There was a medieval church on the site from 1174. This was rebuilt in 1437 and the tower was struck by lightning in 1561. Before the Reformation the patronage of the church belonged to the Abbot and Chapter of Westminster till 1540,then till 1554 to the Bishop of Westminster, when it passed to the Bishop of London and then to the Chapter of St Paul's, with whom it remains. These patrons are represented in the stained glass windows in the north wall.
In 1643 William Penn, whose son founded Pennsylvania, USA, was married in the church. On 4th September 1666 the Great Fire of London engulfed St Martin's which was gutted. Rebuilding was not immediate, was largely completed by 1680, but not finally till 1703. At the same time the church was set back from the old site, as Ludgate Hill was widened.
In 1890 the three parishes of St Martin's, St Mary Magdelene Old Fish Street, which had been burnt down in 1888 and not rebuilt, and St Gregory by St Paul's, destroyed by the Great Fire, were united (See the paintings to the right of the altar).
1894 saw major rebuilding and alteration giving to St Martin's much of the layout it has today. The floor level was raised at the east end, creating the chancel area.
In 1941 an incendiary bomb damaged the roof, but St Martin's received the least damage of all the city churches in the war.
In 1954 St Martin's became a Guild Church (ie it does not have a parish but has other responsibilities and functions). It also became the ward church of Farringdon Within in the City of London.
1962 saw St Martin's become the Chapel of the Honourable Society of the Knights of the Round Table whose history is ancient, although evidence is only patent from 1720.
A major renewal of the fabric, spire and roofs was completed in 1990. Redecoration, renovation of lighting and heating followed, prior to a formal reopening on St Martin's Day, 11th November 1992, in the presence of T.R.H. the Duke and Duchess of Gloucester.
In the 21st century St Martin's exists to serve the local working community, and to provide for the Guilds, Companies and individuals who wish to use the church for their services and events. Further restoration projects are currently planned.