File:Grainthorpe, St Clement's church interior.jpg

English: The church dates from circa 1200 onwards, and was restored in 1876 when the chancel was shortened.

Originally the church was much nearer the sea, when Grainthorpe was an important port. This is why the church is dedicated to Saint Clement, patron saint of sailors.

It is built of stone and rendered.

There is a western tower, nave with north and south aisles, clerestory, chancel and south porch.

The fifteenth century tower is of four stages with battlemented parapets and eight pinnacles with gargoyles. There are three bells.

The nave has four bay arcades dating from circa 1200, the arches, octagonal piers and capitals are from the fourteenth century. The base of the pillars is an unusual claw design.

The north aisle has an early fourteenth century window, the roof has mediaeval bosses. There is also an aumbry and piscina.

The south aisle has steps to an original rood screen and a piscina, denoting a chapel at the east end. There are two windows with Victorian stained glass which was installed in 1993.

The chancel has a fourteenth century brass cross which is incomplete, the base of which depicts a rock of Golgotha above a sea with fish. This is probably to Stephen de See who was rector at the end of the 14th century. There is a mediaeval stone altar and a decorative tiled floor.

At the west end of the nave is a gallery upon which stands the organ. The nave has remnants of Georgian box pews, some with graffiti.

There is a south porch which was long redundant, but has recently been restored and a toilet added. The north door which is the entrance to the church has a fine ogee arch from the 14th century. The door is dated at around 1285 but thought to be much older.

In the nave there is a display of lead taken from the roof with 18th-century graffiti.

There is a plain fifteenth century font.

In 2015 the church secured over £200,000 in funding from the National Lottery which was used for restoration of the church and addition of a toilet and kitchen. The organ was also restored.