It rises in the Löwenstein Mountains and after 26.3 kilometres (16.3 mi) distance and 315 metres (1,033 ft) elevation drop flows into the Neckar at Bad Friedrichshall, near Untereisesheim and Neckarsulm.

The name Sulm is indisputably attached to the river that proceeds from the confluence near State Road 1111 of the Sauklinge and the brook flowing from the Bleichsee.

From that point it flows north on the edge of the Teusserbad section of Löwenstein and past Castle Lautereck, built in 1623; it is in an underground culvert for a short stretch crossing the property of the Teusser company.

After passing under the B39, at an altitude of approximately 222 metres (728 ft), it is dammed to form the Breitenauer See, an artificial lake or detention basin 40 hectares (99 acres) in area which was created in 1975–80 for flood control.

Northwest of the Weiler section of Obersulm, the former bed of the Sulm is now fed only by springs and drainage discharge pipes, while the river flows under the dam in a culvert to a point north of the Weiler–Affaltrach road, where it flows into the old mill stream of the Affaltrach mill and after a few dozen metres into the Schlierbach, a tributary via which it rejoins the original riverbed a few metres further on.

The Sulm flows along the north-east edge of Ellhofen, under the Hohenlohe Railway, and then directly north-west through the territory of Weinsberg, although it does not pass through the town itself.

At this point the Sulm previously flowed in a wide curve to the north and then the west through the grounds of the NSU Motorenwerke plant; following two floods in 1970, it was diverted into a culvert in 1973–75.

NSU Motorenwerke originated in a sewing machine company that began operations in 1880 at the Brunnersche Mühle, a sawmill and gypsum mill in Neckarsulm, and used the river for power.

Prior to the flood control measures on the upper Sulm, during one high water on 18 June 1978, it reached almost 60,000 litres (2,100 cu ft) per second.

Floods occurred regularly, were exacerbated by increasing ground sealing, and presented a problem for the industries located between the Sulm and the Neckar in Neckarsulm.

After two high waters in February and May 1970 flooded the Audi NSU plant, which was of great economic importance to Neckarsulm and the region, and led to a 14-day interruption of production, the State of Baden-Württemberg decided to institute flood-control measures.

These measures have considerably mitigated flood damage, for example during a heavy rainfall on 5 July 2006 of up to 86.4 litres (3.05 cu ft) per square metre.

[8] Since 1979, the upper Sulm valley has been designated as a protected area, Oberes Sulmtal mit Randhöhen,[9] and it lies within the Swabian-Franconian Forest Nature Park.