Aloe arborescens is a large, multi-headed, sprawling succulent, and its specific name indicates that it sometimes reaches tree size.
A typical height for this species is 2–3 metres (6.6–9.8 ft) high. Its leaves are succulent and are green with a slight blue tint. Its leaves have small spikes along its edges and are arranged in rosettes situated at the end of branches.
Flowers are arranged in a type of inflorescence called a raceme. The racemes are not branched but two to several can sprout from each rosette. Flowers are cylindrical in shape and are a vibrant red-orange color