The house that visitors see today presents a confident face of Elizabethan Revival architecture, all symmetry and dressed stone, but behind that nineteenth-century styling lie portions of a much older residence, its front elevation and other remnants quietly incorporated rather than demolished.

The visible house began to take shape in 1820, designed by Sir Richard Morrison for the 10th Earl of Meath. Morrison was one of the most prolific architects working in Ireland during that period, and the commission at Kilruddery saw him working in the Elizabethan Revival manner, a style that self-consciously evoked Tudor England through tall chimneys, mullioned windows, and formal massing. The result was built around and over what remained of the earlier seventeenth-century house on the same ground, retaining certain structural elements rather than clearing the site entirely. The house was then substantially remodelled again in the 1950s, meaning the building has passed through at least three distinct phases, each one folding the previous into itself. It sits on gently undulating land beneath the Little Sugarloaf mountain, that modest but distinctive peak forming a consistent backdrop to the demesne.