The history of St Mary’s, Mundon is typical of many small Essex churches. The manor of Mundon was taken from the Anglo Saxon Godwin, a Kings thane and given to Udo Dapifer at the Conquest.  For over 400 years it was part of the estates of St Johns Abbey, Colchester until, with the Dissolution, it was passed to Thomas Cromwell and after his execution the building passed to the Duchy of Lancaster which held the right of presentation to the vicarage until this century. The farmland was passed into lay hands.

The church is built within the moat of Mundon Hall, a sign of early, possibly Norman foundation. Although the earliest feature in the stone nave is the 14th century north-west window, the font  (now removed) has been dated to c. 1200. In early Tudor times (the 1500s) the timber West belfry was erected, together with a chapel to the south and the tine north porch, but after that the church was not well looked after.

By 1684. the church had fallen into disrepair. It was not rebuilt until the early 18th century, using brick on the original foundations. It is probable that the box pews and painted texts on the walls are of this period. The church was to serve the people of Mundon, although the heart of the village gradually drifted away from the marshland to be centered around the area of the village inn (now the White Horse) post office and later the village pump.

With the rural decline came neglect of the structure and damage by the blast from a nearby v-weapon during the war; fewer parishioners proved willing to make the journey to the isolated unheated and barely lighted church. Services were held in the Parish Room  in West Chase, (demolished in 2004) and although the church was rededicated in 1949 after repairs, the church was virtually abandoned to its fate. The last burial was in the 1950s and by 1957 the graveyard was overgrown and the roof and nave open to the elements. The parish was then amalgamated with Latchingdon and demolition seemed certain.

In 1974, the parish was transferred to St Mary’s at Maldon and the following year the church was adopted and made safe by the efforts of the Friends of Friendless Churches who now lease the property and keep in repair as an Historic Monument.