Bad Salzuflen lies on the eastern edge of the Ravensberg Basin, at the confluence of the rivers Salze (Bega) with the Werre. In comparison to other North Lippe communities it is densely populated. The city centre is surrounded by districts with a village like feel to them and agricultural land. North east of the River Werre and Salze (Bega) runs a strand of the Lipper highlands runs through the largely wooded hills with elevations up to 250 meters in the city. The lowest point is on the border of the River Werre at Herford at about 70 meters. Since 2008, the city is part of the Teutoburg Forest Nature Park / Eggegebirge.
The municipal area is crossed by the river floodplains of the Werre, and Salze. Podzol and Stagnosol brown soils prevail as soil types. The podzolic soils are mainly found in layers from the Tertiary Period, which are crossed by fault block from the Mesozoic. Characteristic of Bad Salzuflen are the saline springs that emerge at these geological folds and which give the region the name of "Germany's healing garden".