Hibiscus brackenridgei subsp. mokuleianus is a tree that can grow up to 10 meters tall. The young branches are covered in prickly, densely stellate pubescence, often adorned with scattered, reddish to yellowish, spreading, simple, spinescent hairs with pustular bases. The leaves are simple, alternate, and show heteroblastic (significant and abrupt change in form and function) development, with midpoint leaves being ovate or 3-5-lobed, measuring 5-14 cm by 4.5-12 cm. The upper plant leaves range from bract-like and oblanceolate to shallowly lanceolate to ovate, 3-5-lobed, 15-60 mm long by 8-80 mm wide, with varying apex shapes. The leaf base ranges from truncate to cordate at the midpoint, becoming cuneate for bract-like upper leaves. The nectary is variable across the leaves, and the margins are serrate to dentate. Petioles at the mid-plant are 3-8.5 cm long, and those at the upper plant are 0.8-9 cm long, exhibiting fine stellate-pubescence. Stipules are filiform, measuring 3–15 mm long. The flowers are solitary, axillary, sometimes clustered near the apex, with peduncles that elongate in fruit and are densely pubescent. The calyx can elongate up to 35-40 mm in fruit, with long-acuminate lobes. The corolla is yellow with a basal spot on each petal, obovate, 3.5-4.5 cm long by 2-4 cm wide, and stellate-pubescent on the dorsal side. The staminal column is prominent, with a length of 20-40 mm, and the ovary is superior, supporting multiple ovules per cell. The fruits are loculicidally- dehiscent capsules 12-20 mm long by 12-17 mm in diameter, with a 1-3 mm beak. The seeds are 3-4 mm long and  2-3 mm wide, angular-reniform, light to dark brown, with honeycombed markings and potentially fringed with hairs. It is found in dry forests and shrublands at elevations of 0–370 meters.