Plants caulescent, densely shrubby; stems to 200 cm tall, erect to ascending. Leaves in a fairly dense rosette on upper 30 cm of stem, to 45 cm long, 8 cm wide, lanceolate-attenuate, grey-green, usually unspotted margins toothed; teeth to 4 mm long, 5-15 mm apart, brownish. Inflorescences to 60 cm tall, with 6-8 branches; branches to 8 cm long, the flowers in a capitate cluster; bracts about 7 mm long, 3 mm wide; pedicels about 18 mm long. Flowers scarlet, pendulous to nutant; perianths about 32 mm long, 8 mm wide across the ovary, outer tepals free for about 9 mm; anthers exserted 2-3 mm; ovary about 7 mm long, 3 mm wide; stigma exserted about 4 mm.
Aloe rabaiensis grows in woodland at about 120 m. It is known from region S3 of the Flora of Somalia and Kenya and northern Tanzania.