The church has a late 11thc. or early 12thc. aisleless nave and chancel, both with plain round-headed windows on the N. The chancel was extended in the 15thc. and the W tower was probably also constructed at that time. Late 11thc. to early 12thc. sculpture is found on S and W doorways, the chancel arch and W tower arch.

The Domesday Survey does not mention a church at Kensworth, but records that the Canons of St Paul's, London held land there. Both Kensworth and nearby Caddington were held by St Paul's until 1872 when the Eccesiastical Commissioners took over responsibility for them. (VCH, 231)

The parish of Kensworth was transferred to Bedfordshire in 1897, but was originally in the hundred of Dacorum in Hertfordshire.

Although no architectural features suggest a date earlier than the late 11thc. much of the sculpture at Kensworth has its origins in pre-Conquest traditions and the church may be described as Saxo-Norman Overlap.

The carving on the S doorway (L capital S face) probably represents the wolf and crane story from Aesop's Fables, whilst the carving on the L capital E face could be the story of the Kite and the Serpent.

VCH likens the four carved birds on voussoir 13. of the tower arch to those found on pennies of Edward III. (VCH, 233)

In 1911, whilst repairs were being made to the N wall of the chancel, the remains of a ground-level window were discovered below the easternmost chancel window. A fragment of the window arch survived, which was carved with a shallow roll, as were the two chancel windows above. Smith suggests that this low window was an anchor-hold. (Smith, 74). In support of this he noted that the window arch fragment made no allowance for the insertion of glass, and that fragments of a wooden shutter were found in the rubble. The arch fragment was reset in the window opening when the area was refilled and stabilised.

Cussans records that when 'Oldbury' a building adjoining the church, was rebuilt in 1877, stones with 'dog tooth moulding' were found in the walls.

In 2002 when Kensworth was revisited, all windows in the N wall had been completely restored.

VCH suggests that the plain font may be 12thc.