In the eighteenth century as the Georgian streetscape of Dublin was being developed, the castle was redeveloped also. A young architect believed to be Sir Edward Lovett Pearce redesigned the upper yard using the basic design inherited from Sir William Robinson. These ranges constructed in the 1680s and shown below are similar to those present today.

The Genelogical Office or Bedford Tower (in the picture) was constructed around the 1750s along with its two flanking gateways to the city. The clock tower is named after the Duke of Bedford, John Russell who was the Lord Lieutenant and is constructed on the site of one of the original towers. The State Apartments for the Viceroy were constructed and the upper yard laid out as it exists today.

In the 19th century, an attic storey was constructed in place of the dormers. In 1779 it was stated that 'this castle is far superior to the palace of St James's as well as in the exterior, as to the size and elegance of the apartments within'.