Kirkby Lonsdale is not unusual in north-west England for its great width, as the larger parishes of the 14thc. led to a need for extra aisles. What is unusual is the scale of its earlier, pre-Perpendicular work. The church has a very showy aisled 13thc. choir with an E counter-facade of rich Early English ornament. This is still out-done by the Romanesque work, with its three full-length arcades in a clean rectangle. The earliest section is the N arcade which clearly echoes Durham Cathedral at some remove. The later S arcade is Transitional late Romanesque, and probably goes with the priest's door preserved in the S aisle of the current chancel. The major W portal and S doorway are mid- to late 12thc..

The church has been much altered: a 16thc. clerestory above the Romanesque arcades has been added and removed, meaning the walls above the Romanesque arcades are all rebuilt. The biggest interference to the Romanesque fabric seem to be the 1705 reconstruction of the tower, attested by a date stone, when work was probably done on the west portal. However, Neo-Norman replacement is confined to the ringing gallery on the E face of the tower; otherwise the sculpture is occasionally damaged but untouched by restoration efforts.

In the 1090s Ivo de Taillesbois gave the church and its land to St Mary's Abbey at York, which kept it as an appropriated vicarage. The parish had the usual high income for the north-west, assessed for tax in Domesday at 43 geld units, and in the 1292 Taxation at £102,14,13.

Comparisons are usually made between the monumental N arcade and Durham Cathedral. While these are certainly evident, Malcolm Thurlby has argued that the ideas may have been mediated through other buildings, such as Selby Abbey nave and fragments from St Mary's Abbey, York.

The fact that the institutional rectors were from St Mary at York is not sufficient to explain the ambition of the early 12thc. work. Such a plan is probably connected to the existing status of the church at the time of the Conquest, as it may have been a particularly ancient Saxon foundation and/or a minster church with a relatively large clerical staff.