Lignotuberous tree or shrub, 0.4–10 m high, with epicormic buds. Fl. yellow, Oct–Feb.B. attenuata was first collected by Robert Brown from King George Sound in 1801.. Aboriginal people placed the flower spike in a paperbark-lined hole filled with water to make a sweet drink. Both this species and Banksia aemula have been credited with the inspiration behind May Gibbs "Big Bad Banksia Men"
It was said it is probably the most ancient living banksia species in the SW of WA - fossilised cones have been dated as 18 million years old. The oldest banksia cones (of a banksia species that is now extinct) is 61 million years old. Banksia attenuata is long lived - up to 300 years old. It can also hold viable seed in its cones for many years - up to 12 years has been recorded. Banksia attenuata flowers out of phase with Banksia menziesii to provide provide a more continuous food source for pollinators, being mostly birds and insects.