Sedum hispanicum is a glabrous or somewhat pubescent annual, 5–15 cm tall. Its stems branch. Its linear leaves are alternate, 7–10 mm long and rounded. Its flowers are usually six-parted, sometimes 7–9-parted, arranged in unilateral cymes. Its sepals are ovate-acute. Its white petals have a purple midrib, and are 5–7 mm long, lanceolate and acuminate. Its carpels are stellate. It flowers from March to June.