The motorway begins at Redbridge near Totton at a grade separated roundabout with the A35, heading north, briefly as a dual three-lane motorway.

At its first junction, it reduces to two lanes and continues east of Hillyfields.

After a further 1 mile (1.6 km) it reaches a junction with the M27 at a signal controlled roundabout.

North of the M27 it enters the countryside and terminates after a further mile of dual two-lane road at another roundabout, this time with the A3057 near Upton.

In 2019, improvement works to Redbridge Roundabout at the southern end, introduced a dedicated lane to connect the M271 with the A33 towards the docks in a free-flow interchange.