[4] Acacia gunnii is a woody decumbent to erect shrub up to 1 meter in height, branchlets are terete usually covered with stiff hairs.

[6][3] Dark green phyllodes are asymmetric, can be sessile, variable in shape usually with a pronounced gland on adaxial margin near or below middle.

[6][8] Phyllodes are 4-15mm long and 1.4-4mm across and appear glabrous or finely haired with a prominent mid-vein, sometimes the apex pungent pointed.

[6][8] Inflorescences are simple with 1 in the axis of phyllodes, peduncles are hairy, 4–15 mm in length with the head being globose, 20-30 flowered, cream to yellow coloured, and 5-8mm in diameter.

[14] It is most abundant in regions of partially disturbed and open rocky habitat with sparse understory, commonly, along track/road edges.