The parish of Streatley has a long history going back to Anglo Saxon times. Following the Norman conquest of 1066, Geoffrey de Mandeville was made Lord of Streatley Manor for his valour at the battle of Hastings. It was he who made a generous gift of land to support the priest, and it was he who appointed Wibert as Priest of Streatley in 1086.
The present church and chancel were practically rebuilt in 1864. Some additions were made to the tower, which was originally built in the 15th century: the turret staircase on the south side and the demolition of the original cupola which housed the Sanctus bell (circa 1549). It now hangs at the back of church.
At the beginning of the 19th century, St Mary's was in a very poor state of repair but it was extensively restored in the mid 19th century under the auspices of a Mrs Stone, who was the lady of the manor at Streatley House in the High Street. The chancel was rebuilt by the lay rector, S Pusey, Esq. In 1893, the fine Victorian reredos was erected in grateful memory of Mrs Stone. The reredos is a beautiful design in alabaster by JL Pearson RA. Besides the reredos there are a number of memorials to the Stone family. Both the east and west windows are in memory of William Henry Stone (1863).
During the 19th century rebuilding work, many of the original 13th century materials were used, such as, flint (a local material) and stone. The clerestory is an addition, the extra windows increased the light and ventillation. The columns of the nave and aisles were built in alternate bands of cream Bath stone and Berkshire chalk. In 1864 Samuel Wilberforce, Bishop of Oxford, consecrated the restored church.
Under the tower arch is a marble wall slab to Sophia Small, of Chalford, Gloucestershire, spinster 1783. Near this is a tomb with painted crest, to Samuel Rush (1771). At the back of the church there is a brass plaque, which lists the Vicars of Streatley dating back to 1307, when John de Whicheford was presented with 'the tithes of the Manor at Streatlee'.