Dubautia waianapanapaensis is a large, usually diffuse shrub that grows up to approximately 4 meters tall. The branches are woody, and the vegetative shoots are glabrous, except for being ciliolate at leaf scars or, more rarely, sparsely or moderately hispidulous. The leaves are opposite and spreading, oblong-elliptic to usually oblong-oblanceolate, measuring 4-12 cm long and 0.5-2.2 cm wide. They are usually 5-9-nerved and often show impressed reticulation on the upper surface. The leaves are appressed puberulent basally along the impressed veins on the upper surface, otherwise glabrous and eglandular. The margins are usually 3-8 denticulate, typically above the middle, setose ciliate, or ciliolate. The apex is acute, and the base is usually sessile and sub-clasping. The flower heads number around 5-30 in lax, racemose to simple, paniculate inflorescences, usually 5-25 cm long and 4-10 cm wide. The peduncles are hispidulous to villous, with the ultimate ones typically 0.3-3 cm long. The receptacle is flat to low convex, with a false involucre consisting of a single series of 9-14 peripheral, somewhat firmly connate receptacular bracts, usually 6-10 mm long, glabrate to pilosulous, eglandular to sparsely glandular. The florets number around 7-30 per head, with yellowish-orange corollas that are 4-7 mm long, glabrous, and eglandular. The pappus consists of usually 16-22 very narrowly linear, ascending setose bristles, usually 4-7 mm long. The achenes are usually 4.5-6.5 mm long and glabrate. It occurs in wet forests between 1,525-2,275 meters.