While stretches of the road before Randalstown have now been superseded by a motorway (the M2 and M22), the A6 remains one of the most important arterial routes in Northern Ireland, connecting its two largest cities and urban areas.

Much of this section is urban in character and there are many two-lane stretches, allowing vehicles to overtake or bus lanes operating at peak times or rush hour.

The A6 then passes through the suburban district known as Mallusk which forms the outer-most periphery of the Greater Belfast urban area, characterised by industrial estates.

It passes under the Belfast-Derry Railway Line, through Templepatrick village (via a multiplex with the A57 Ballynure-Aldergrove road), Dunadry and then enters Antrim town.

As of 2023, 26.5 miles (42.6 km) of high-quality dual carriageway on stretches of the route between Belfast and Randalstown and Derry and Dungiven have been constructed through the A6 Dualling Scheme at an estimated total cost of £420m.