The A297 is a short link road located principally in the south-east corner of the London Borough of Merton.
Starting from a roundabout junction with the A24 outside the National Trust-owned Morden Hall Park, it runs southward for two kilometres to meet the A217 at Rosehill, just inside the borough of Sutton.
The route is primary and, apart from a very short section of Morden Hall Road on the approach to a roundabout junction with the A239, is also dual-carriageway throughout. Beyond the A239 the name changes to St Helier Avenue and the road quickly becomes arrow-straight for the whole of its second half.
The A297 did not feature in the original 1922 Road Lists, but had appeared by the time that the A217 Sutton bypass was opened and St Helier Avenue (a northern extension of Rose Hill) was developed, towards the end of the 1920s. It took over the route of the former B276 from Morden Hall to Morden Lodge, ran along the new St Helier Avenue, and then the old, pre-bypass route of the A217 through Sutton. The last of those three sections has since been reclassified as the B2230.