Acacia crombiei is a tree that typically grows to a height of up to and has twisted, glabrous branchlets. The phyllodes are narrowly linear, straight to slightly curved, mostly long, wide, narrowed at both ends and leathery with the midrib and edge veins prominent. There is an oblong to more or less linear
gland long, up to above the base of the phyllode. The flowers are borne in up to four spherical heads on
peduncles long. Flowering has been recorded in April, May, August and October and the pods are narrowly oblong, firmly papery to thinly leathery, up to long and wide with knob-like protuberances along the midline. The seeds are oblong to widely elliptic, dark brown and slightly shiny, long and wide. This species of wattle is reported to have a habit that is similar in appearance to
Acacia cana or
A. cambagei. ==Taxonomy==