- The Castleknock ward of Fingal Co Council which I represents includes all of Castleknock as far East as the Halfway House Pub and as far South as Knockmaroon Hill.
- It includes all of Blanchardstown as far west as Shelerin Road and Blakestown Road. This includes estates such as Limelawn, Sorrel, Aspen, Lohunda, Fortlawn, Whitestown, Sheepmore and Whitechapel.
- Waterville is the only place north of the N3 that is within the Castleknock Ward.
- The ward includes all of Carpenterstown and Porterstown as far west as Laragcon.