Dillwynia acicularis is an erect shrub that typically grows to a height of with hairy stems. The leaves are erect, narrow linear, sometimes triangular in cross-section, long with a longitudinalgroove on the uppersurface. The flowers are arranged in racemes on the ends of branchlets with leaves at the base, and hairy bracts and bracteoles about long. The sepals are long, and the standard petal is long and the keel is yellow with red markings.