St Mary's Church building was completed in 1861 and consecrated on 9th May, Ascension Day of that year. Since then it has undergone many carefully renovations. Prior to being built services were held outside the old barracks in Georgetown and usually conducted by the senior officer of the garrison. Inside are plaques commemorating many who died on the island both at sea and from illness. The church holds historical records of island births, marriages and deaths.
It retains contemporary social significance for the local community and those abroad being used for weekly worship, weddings, baptisms and funerals. The chaplain of the island was originally provided by the Royal Navy, then Royal Air Force and nowadays from the Anglican Church, Diocese of St Helena, Province of South Africa.