St Mary's Church is the parish church of Old Hunstanton in the English county of Norfolk. It is dedicated to the Virgin Mary. The church was built in 14th-century Perpendicular, and restored in 1860 by Frederick Preedy at the instigation of Henry Le Strange. It is Grade I listed.
The church is 14th-century, and replaced an earlier Norman building. The only remnant of the Norman church is the font.
The church is built from flint, with a tower in the north west and north and south aisles. The south porch is a 19th-century addition.
The Norman font is in the traditional location at the west of the nave. The lower panels of the chancel screen are 16th-century.
There is a single tenor bell, by John Stephens of Norwich and dating from 1726.
Most of the stained glass dates from the 1860s refurbishment. The five-light east window is generally regarded as Preedy's greatest work. Preedy also designed the three-light Tree of Jesse east window in the south aisle chapel; there are also windows by Powell and Paul Quail.
The organ was built in 1936 by J. W. Walker & Sons Ltd; the organ case was built by Sir Walter Tapper. Walkers undertook various refurbishments and modifications; the most recent refurbishment was by W. & A. Boggis of Diss in 2008.
The church is home to a roost of common pipistrelle and soprano pipistrelle bats.