St Laurence's has a three-bay aisled nave without clerestoreys. The N aisle and arcade date from 1850, the S has elaborately carved 12th-13thc. capitals, at the very least heavily restored in the 19thc., carried on piers of a variety of forms. The arches above are 13thc. The chancel was rebuilt by J. M. Derrick in 1848, with no chapels or vestries. The W tower is 12thc. in its lower stages, with a plain 12thc. doorway to the S, but heavy buttresses and a top storey were added, probably in the 15thc. In 1999 a kitchen and lavatory block was added to the N of the tower, communicating with the N aisle. The church also contains a font, stylistically 12thc. but suspiciously crisp and regularly carved.

In 1086 Brafield-in-the-Green was apparently disputed between Countess Judith, who held three virgates and whose tenant Winemar held one virgate, and the Bishop of Bayeux's tenant William, with three virgates claimed for the Countess by Nigel. No church is noted in any of these holdings.

Dedication to St Lawrence recorded in 1529.

The decoration of the arcade capitals includes features associated with the 12thc. (basketweave, palmette decoration, knotwork and waterleaf) alongside a repertoire of motifs and forms which belong well into the 13thc. (inhabited stiff-leaf). The impost forms are more likely in the 13thc. than the 12thc. When the arches were replaced in the 13thc., it seems likely that the imposts were too, along with the whole of pier 2 and all the capitals except that of pier 1. The W respond capital and its impost were either heavily restored or (more probably) replaced in the 19thc. The E respond is largely original, but restored. Pevsner described the font as 'big, Norman', and the List Description calls it Norman, adding that it is 'probably recut' but the present author agrees with the VCH that 'the font is modern', probably a 19thc. piece. The blocks are very precisely cut (see dimensions of bowl), and the carving is entirely regular on each face. Furthermore it shows no signs of lock damage on the rim, which would be expected in any 12thc. or 13thc. font.