It runs south west from Edinburgh for approximately 70 miles, through Saughton, Wilkieston and south of Livingston, Whitburn and Wishaw, then by way of Overtown, Garrion Bridge, Stonehouse, Strathaven, Darvel, Newmilns, Galston, Hurlford and Kilmarnock to Irvine on the North Ayrshire coast.

The A71 climbs steeply up the western side of the Clyde valley on a road which it shares for a very short section with the A72.

At Darvel, the A71 becomes a primary route for the rest of its length to Irvine, and widens slightly, with a straighter alignment until its junction with the A77, south of Kilmarnock.

A crash barrier runs along the central reservation of the dual-carriageway from the A77 to the boundary with North Ayrshire at Dreghorn.

In mid 2014, the road began to subside between Darvel and Newmilns, with the westbound lane being affected near to the entrance to Gowanbank House.