Aloe neilcrouchii has a long, sprawling to erect, leafless stem that can grow up to 950 × 90 mm and which branches from the base, forming very evident off-shoots. The leaves are lost on an annual basis (deciduous); they form a dense rosette at the tip of the stem and the old leaves do not persist. The leaves are green and have many white, elongated, tuberculate spots on both surfaces. They are deltoid to ovately lanceolate, up to 430 mm long and 135 mm wide at the base, with small, irregularly spaced, white teeth along the margin, 1–2 mm long and 2–5 mm apart. When broken, the leaf gel is clear and dries clear, and is not bitter.

Flowering time is in midsummer (December to February), and one, unbranched, erect inflorescence is produced per rosette. The flowers are tubular, about 45 mm long, salmon-pink with green tips, in dense heads about 120 × 100 mm, erect in bud and spreading to nodding when open. The fruit is an oblong capsule, bright green to yellowish green, up to 40–45 × 22 mm. Seeds are angular, black, 3 × 2 mm with a semi-transparent, light brown wing, about 1 mm wide.

Aloe neilcrouchii may be confused with Aloe boylei, but can be distinguished by its long, sprawling, leafless stems (those of A. boylei are stemless to up to 20 mm long) and its shorter but broader, copiously white-spotted leaves.