The N9 road is a national primary road in Ireland running from Junction 11 on the M7, located near Kilcullen, County Kildare, to Waterford city. The route connects Dublin and Waterford. The section of the route from junction 11 on the M7 at Kilcullen to the intersection with the N24 road outside Waterford is motorway standard since 2010 and is designated as the M9 motorway. In line with Irish practice, all sections previously designated N9 were renumbered at that time. Only a short (550-metre) section of the route is still designated as N9 between the Quarry roundabout junction with the N24 and the N25 Grannagh Roundabout junction. This section is dual carriageway.

A national primary road is a road classification in Ireland. National primary roads form the major routes between the major urban centres. There are 2649 km of national primary roads. This category of road has the prefix "N" followed by one or two digits. Motorways are prefixed "M" followed by one or two digits.