This perennial thistle grows up to 1.5 metres tall and is distinguished by its creeping horizontal lateral roots, which produce dense patches of stems. The dark green leaves are deeply lobed, sessile and prickly, and sometimes hairy on the underside. Each flower head is 1 to 1.25 centimetres long and contains numerous pale purple to lilac florets.
The creeping thistle grows in open, mesophytic habitats, thriving, where sufficient light is available, in all but waterlogged and poorly aerated soils. Patches of creeping thistle are common in areas of disturbed soil such as agricultural land, roadsides, ditch banks and overgrazed pastures.