St Mary's Church is a Grade I listed parish church[2] in the suburb of Prittlewell in the city of Southend-on-Sea, in the ceremonial county of Essex, England.

It is the largest and one of the oldest churches in the county.

The church is open for worship, while community events aree held in its hall.

[3] The church was founded in the 7th century as a chapel by the Saxons.

From the 12th century until the 17th century it was extended and became the largest church in the county of Essex, as well as one of the oldest churches in the county.