The church of St. Peter and St. Paul, Horndon on the Hill is a Grade I listed building, situated on top of a hill, possibly on the site of a Saxon church. The present building dates from the 13th century. The walls are predominantly of Kentish ragstone and rubble with some brickwork. The windows and doors are dressed with Reigate and other limestone.

The church takes its name from the Apostles Peter and Paul and the villagers celebrated their feast on 29th June with an annual Fair granted by Royal Charter by King Edward I. The annual feast and fair on the last weekend in June was revived in 1974.

An avenue of polled lime trees lead to the much restored 15th century porch. The church has a 13th century doorway. The nave, aisles and chancel are largely unchanged over the last 700 years and all show evidence of 13th century workmanship. The nave is separated from the aisles by 4 bays . Some columns are cylindrical; some hexagonal. Some have plain capitals; others have decorated capitals with carvings of foliage etc. There were formerly extensive paintings visible on the columns and walls above the arcades, but now only small patches of colour remain.

Over the north arcade are two clerestory windows as old as the church. Over head is an 18th century roof supported by two15th century king-posts. The church is dominated by massive oak beams supporting the 15th century bell tower. There is a modern lectern on a brass dome.

The floor of the nave consists mostly of memorials to members of local families of the 17th and 18th centuries. One of the memorials has a mistake on it. It shows the lady's age as 303 instead of 33.