Inside, there is seating for 400 people. There is a memorial plaque to the author Henry James (1843–1916) who lived nearby on Cheyne Walk. To the west of the church is a small public garden containing a sculpture by Jacob Epstein.
Chelsea Old Church dates from 1157. Formerly it was the parish church of Chelsea when it was a village, before it was engulfed by London. The building originally consisted of a 13th-century chancel with chapels to the north and south (c.1325) and a nave and tower built in 1670.
The chapels were private property. The one to the north was called the Lawrence Chapel and was owned by Chelsea's Lord of the Manor. The chapel to the south was rebuilt in 1528 as Sir Thomas More's private chapel. The date can be found on one of the capitals of the pillars leading to the chancel, which were reputedly designed by Holbein. There is a statue by Leslie Cubitt Bevis of More outside the church, facing the river.
There is a 1669 memorial to Lady Jane Cheyne. It was designed by Gian Lorenzo Bernini but executed by an apprentice.
It is the only London church to have chained books. They are the gift of Hans Sloane and consist of the so-called "Vinegar Bible" of 1717, two volumes of Foxe's Book of Martyrs (1684 edition), a prayer book (1723) and Homilies (1683).
The church suffered severe bombing during the Blitz of the Second World War in 1941, with the More Chapel least affected. Services were held in the adjoining hospital for nine years. In 1950 the More Chapel was reopened, followed by the chancel and Lawrence Chapel in May 1954, after restoration by the architect Walter Godfrey. In May 1958, the entire church was reconsecrated by the Bishop of London, in the presence of Queen Elizabeth the Queen Mother. The Church has been restored in its entirety on its old foundations. It looks quite different from the way it did before World War II, as it is now clad in red brick, whereas it was previously a white building. The brickwork was necessary because so much was destroyed. Some of the tombs inside have been reconstructed, almost like jigsaw puzzles.