St Helen's is the parish church of Kelloe. The nave and tower are 11th century in date. The chancel is 13th century in date, but was largely rebuilt in 1854 and refitted 1901 by W.S. Hicks. A side chantry chapel known as the Thornley Porch was founded in 1347 and restored in 1691. It was converted into an organ-chamber in the late 19th century. The church has a late 18th century vestry and early 19th century porch.

The St. Helena Cross, built into the north chancel wall, is a richly-carved, probably 12th century stone cross with 3 panels illustrating the legend of the Invention of the True Cross with associated saints Helena and Constantine.

The church is known to contain at least two features dedicated as war memorials.