Banksia dallanneyi is a shrub that sometimes grows to a height of and has a fire-tolerant, underground stem and only a short above-ground stem. It has pinnatipartite or pinnatisect leaves that are long and wide on a
petiole long. There are between ten and eighty triangular to oblong lobes on each side of the leaves and the lower surface is covered with woolly white hairs. The flowers are arranged in heads of between thirty and seventy with linear to lance-shaped
involucral bracts long at the base of the head. The flowers have a cream-coloured, golden yellow or pinkish
perianth long and a cream-coloured, pink or maroon
pistil long. Flowering occurs from May to October and the fruit is an egg-shaped, mostly
glabrous follicle long. ==Taxonomy and naming==