Santalum haleakalae var. lanaiense is a small evergreen tree that reaches heights of 1 to 6 meters with either single or multiple stems and exhibits hemiparasitic behavior on the roots of other plants. Older trees can spread vegetatively through root sprouts when surface roots are exposed or damaged, occasionally forming small groups. The leaves are simple and opposite, with blades ranging from narrowly to broadly ovate to elliptic and sometimes conduplicate–falcate, measuring (3.4–)4.4–6.8(–8.4) cm in length by (1.0–)1.6–3.1(–4.9) cm in width. These leaves feature an acute or obtuse apex and a cuneate base and are more glaucous and paler on the lower surface. The surfaces are light, evergreen, olive to dark green, ranging from chartaceous to coriaceous in texture, with flat to slightly recurved margins. Lateral veins on both leaf surfaces are apparent, and petioles range from (3.9–)7.4–15.4(–21.7) mm in length. The flowers are bisexual (perfect), weakly fragrant, and appear reddish to cream-colored in the bud, arranged in fairly dense to dense terminal or axillary inflorescences. Pedicels are 2–4 mm long, and the corolla comprises 4 (rarely 5) petals that are deep pink to red throughout or with white to pink interiors. The floral tubes measure (3.4–)4.2–8.0(–11.2) mm in length. The drupes mature to a black or purplish black color, measuring 10–16 mm long and adorned with a subapical receptacular ring. Seeds are muricate (studded) with a pointed beak on one end. It occurs in exposed or semi-shaded scrublands between 800-1,300 meters.